Is there any application for using three axle powered truck part#6550X-2702, other than an E60CP? ???
Yes.
yes, is answer but which units? and would it need extra modifications?
my guess is that it would also be used under the dash 8s, as most ge 6 axle locomotives used the same two styles of trucks, which were interchangeable and very similar in appearance. every 6 axle ge in north America used those two styles, from the later u28cs of mid 1966 up to and including the very first dash 9s built for csx in 1993.
on the models I haven't tried them as those locomotives are not appropriate for my model railroad. but I doubt Bachmann would go to the expense of tooling up a separate truck when the existing one would be appropriate for the dash 8s and the e60s.