From what I see, you can't get a Gen 7 chassis from the parts store. The only choice now is a Gen 5B.  Something must have happened to the original Gen 7 chassis (i.e. drop/break) and owner had to adopt the Gen 5B or earlier Gen 5. If the pilot truck is a drawbar its Gen 5B, if its a pivoting truck its Gen 5.   Just noticed it has chuff drum so its a Gen 5 chassis.

Mainly from looking at photos on Bachmann parts website.
Starting with this video on Youtube (A Brief Look at the Improved Bachmann G Scale 4-6-0 Front) by RkyGriz.
If you watch carefully you can see that in the new drawbar truck, the axles of the pilot wheels are clearly visible from above.
In the old pivoting truck, the axles are covered by the plastic truck's frame. So you don't see axles from above.
Now go to Bachmann parts store and look at pictures of 90037 and 90040 assemblies.
You can see the axles from above on the pilot trucks, suggesting drawbar pilot truck.
Another data point is the Underframe at the parts store, it has the pivot point structure.
Looks to me like all the older V5 and below chassis, underframes, pilot trucks are sold out and gone for good......
Drawbar Pilot Truck
    https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=8545
Newer Underframe
    https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=14592

Bill, I think your ID "chart" is great, but it relies on almost all mechanical and physical descriptions (i.e. humps and plugs). As electronics has entered both the Annie and Standard lines, its worthwhile to add descriptive features about the electronics and capabilities.  Like the Standard V5B (if 90037/40 are V5B) now contains a PCB that supports only a limited set of features (i.e. no rear tender headlight) and different implementations (i.e. optical chuff sensor vs. older "drum" sensor)
Just my observations as I wasn't sure what constituted a V5B and when/why it came about.

In reviewing chassis ID sticky and looking at "Standard" (not Anniversary) chassis for sale in parts dept.
Is Loco Chassis (90037) and (90040) (Large 4-6-0 Standard) what is being considered as Version 5B?
If so, description for V5B might be enhanced
  Standard Chassis (not Anniversary)
  Connectorized Wiring
  Main PCB (PCB06)
  Optical Chuff Sensor (PCB08)
  Drawbar Pilot Truck
  Plastic Side rods and detail parts
  Smoke Switch (based on what main PCB06 supports)
  LED headlight (based on what main PCB06 supports)
  No Tender Backup LED (based on what main PCB06 supports)

https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_669&products_id=4094
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_669&products_id=12182

These seem to be the only chassis available in the "Standard" line and will require a fair amount of rework (especially soldering)
to rework a V5 thru V2 "Standard" loco.

The chuff drum OR chuff sensor will be on the front driver. Should have one or the other.

The bottom cover (known as Loco Underframe (Large 4-6-0), 900XX-UF-01) contains two long brass strips, left and right that contact the front and rear drivers (the middle is a dummy driver). On a fully assembled underframe (V5B but not V5), the pilot truck wires connect to the brass pickups and then a single pair of wires (track power) go up an into the "chassis".

Underframe
  https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=14592
Brass Pickups (Contacts/Pair Anniversary(Large 4-6-0), G812X-MT010
  https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=8854

So the latest Bachmann "Standard" (non-Anniversary chassis) (it's not v7 or v5, what are we calling it?), has connectorized assembly as as you noted and in the "chassis" there is a central PCB (G912X-PCB06-A) that accepts all the connectors:
  Track, 2-pin connected to wires from base plate containing wheels and pilot truck pickups (so this is power in)
  Motor, 2-pin connected to motor, note polarity noted as M+
  Smoker, 2-pin connected to smoke unit in "shell"
  SW/LED, 4-pin connected to headlight LED in shell and "most likely" to Smoke On/Off Switch under smokebox door. Two functions, LED power and Smoke On/Off.
  SENSOR, 3-pins going to the new chuff sensor on the front driver axle (PCB08). Looks to be optical/IR with a two-blade interrupter plate on front driver axle.
     The 3 pins are VDD (a voltage to the sensor created from track power using a DC/DC converter (see U2), GND, and 'T' which is basically the signal from
       the sensor.
     This optical sensor signal needs to be converted to something the tender can use just like what was created by the chuff drum and contacts in V5 and below.
     This is done by Q1 and the 4-pin device next to it, an opto-coupler whose output transistor is connected to the TRIGGER connector. So a transistor replaces
       the chuff mechanical contacts.
  TRIGGER, 2-pin connector that connects to the small pcb at rear of loco (PCB02) that contains the chuff on/off switch and the two-pin connection to the
     tender to "trigger" the chuff sound board in tender.

So if your chassis still has the chuff drum and pickups on the front driver axle, these two wires to go the rear loco PCB board (PCB02).
If your chassis has the newer front driver AND the sensor board, the sensor board (PCB08) is connected to SENSOR and the TRIGGER is connected to the rear loco PCB (PCB02).

New V? PCB (G912X-PCB06-A)
  https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=14587
New front driver chuff sensor (PCB08)
  https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=14586
New front driver (notice interrupter plates in center of axle)
  https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=10420
Rear Loco PCB (PCB02) supply connection point to tender cable
  https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=10232

 

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Clearly a modified (seemingly well done) of a V7 loco shell with a V5 frame/chassis especially with the wiring. Should be noted that seller also has a 4-6-0 modified to a Camelback. Appears as the original owner was into "extreme" modifications. Why? Only he/she knows. I will say that the workmanship looks pretty good. One thing, I have never seen V7 chassis on Bachmann parts store, so maybe chassis was broken and original owner wanted new chassis from Bman parts so settled for V5 and adapted wiring.

Really need to see a picture of the rear of loco to see what type of connector/cable is present. Since photo shows tender connector unattached, no way to know if even possible to connect. Seller told Fred2179 that he's not really a train guy, so he may not have even tried to connect and run, simply removed from box to take pictures and assumes it all matches and works.

So it is the original box now containing the original tender and the original loco shell.
But for some unknown reason the original chassis has been removed from the original shell and been replaced by an older version chassis that looks in nearly new condition.

In one of the pictures you can see the new, larger, more wires plug indicative of a "Gen 7", so if male plug is on cable coming from tender, then the tender is "Gen 7". But the loco does not match the picture on the box's end-cap in terms of gearing, wheel/driver center color, cylinder decoration, etc.  Loco definitely does not match and fairly certain not "Gen 7". Quality eBay listings usually have many more photo showing many more details. Avoid this item.

Looking at the PCB, I would expect the two wires labeled "Trigger" to go the the rear of the loco where the small PCB with on/off switch provides the connection to the "chuff sound board" in the tender. More appropriate name might be "Trigger Out".  I can tell from the PCB that the chuff sensor (connector is 3-pin) is using some form of optical or hall-effect sensor. The circuity above the connecter is a DC/DC power supply needed to power (VDD) the optical sensor. In addition, near the Trigger connector is a Q1 and square 4-pin device that is probably a solid state relay mimicking the open/close contacts of the old chuff sensor. Since he has the new chassis the chuff sensor should be in place with the 3-wire connector attached.  He then needs to connector Trigger to the locos rear "Sound" connector board.  At this point, I don't beleive polarity matters.

If you're just going for DC track operations, then set aside the PNP board and simply wire as the older gen's. From chassis you will have two motor wires and two pickup wires, connect to shell wires just like Gen4 and earlier.

Agreed and as I was saying the GP-30 has enough rotation to handle R1 so it then becomes a coupler issue.
As to FAs they must not have enough rotation in their trucks to handle R1.
So the first question for OP to answer is does the new GP-40 trucks have enough rotation to handle R1?
If yes, then his next inquiry will be to how well the body mounted couplers will work off-the-shelf on R1.

Well, I see the GP-40 is a two-axle loco and I see no reason why a two-axle truck (as opposed to three-axle) wouldn't work fine on a 4' DIA curve.
Unless, the trucks have limited rotation, but they usually have pretty wide swing.
So my guess is the real issue is coupler length/swing radius.
Depending on distance from truck to body-mounted coupler determines how far coupler extends outside the outer rail in a curve.
If the coupler can't rotate enough then the force direction pulls the trailing car off the track.
Currently running a USA Trains 2-axle GP-30 and this is exactly the problem I encounter, the loco's coupler pulls the trailing car off the track.