Bob,
Picked up the Kadee #452 today at my LHS and spent two hours installing it, which included cutting my finger with the exacto knife.  You need to cut some material off the front of the front of the front truck and the back of the rear truck.  You may also need to file the metal openings where the coupler pocket adapter fits.
The coupler is a Kadee #35 which is not easy to assemble, but can be done with nimble fingers.  It is a short shank, center mount cover.  Luckily I assembled the couplers before I cut my finger.  There are two options for coupling, 5' and 3'.  Putting the wavey spring behind the coupler pocket is the hardest part of the assembly outside of cutting away the material, and finger, from the trucks.
If you have never assembled a Kadee series 30 coupler, read the instructions first.  Kadee's instructions for the whole installation are good.  I did the 5' spacing so I did not bother with the 3' instructions.  However, the front coupler on the A unit is really tight when you use the 5' mounting hole, so I doubt if the 5' mounting hole would work.  It would be fine for the real of the A unit and both ends of the B unit.
I do not see any way you can use the Kadee #148 and its draft gear box on this unit.  Not enough room or any place to mount the box, especially on the front.
If you have any questions, let me know and I will try to answer them.
Wayne

Bob,
Kadee #452 is a replacement coupler pocket for the Bachmann F-7 A and B units.  From the picture on the Kadee web page, it looks like a direct replacement for the Bachmann pocket that pops out the chassis.  I plan to use one of these if my LHS has them in stock.  I do not know which Kadee coupler the #452 uses, but it is supplied with the conversion kit.  I suspect that it is one of the #6, 7, 8, etc. series.  I do not know much about the #148, but it may not work in the Kadee pocket.  The F-7 I am repairing belongs to a young friend of mine and he does not care what type of coupler is on it, all it needs to do is couple.  His grandmother knocked the loco off of his table and the coupler pocket broke when it hit the floor.  I will post the type of coupler when I find the #452.
You can remove the Bachmann coupler by slipping a small screwdriver under the coupler clip and snapping one end off.  The plastic is derlin, I believe, and not easy to break, except when dropped on the floor.  Hope this helps.
Wayne

I finally got the shell off, with no help from Bachmann.  I sort of modified Don's suggestion.  My rule is: "don't force it, use a bigger hammer."  First I removed the front and rear couplers by removing the clip that holds the coupler to the pocket.  Then I removed the four phillips head screws in the chassis at the front and back of the fuel tank.  You will need a small phillips head screwdriver.  Then I spread the sides apart with my fingers and a thin ruler, lifted the back up as far as would go and pulled and pushed until it came out.  I believe the front coupler pocket was the culprit that was holding the shell in.  Hope this works for others.
Wayne

I have contacted the Bachmann service department.  No answer yet, but whatever I get I will post.

How does one remove the shell from a Bachmann F-7A unit.  I have removed the four screws on the base at the fuel tank and the front coupler and still could not get the shell to come off.  What is the secret?  I need to replace the rear coupler pocket and need to get to the chassis.