Lionel /Williams GP shell swap?

I have found the two shells to be inter-changable.  Also picked up a few extra shells at meets and have  one shell that has two different road names, one on each side.

It shouldn't be a problem.  Check out my Lionel u36 shell on a WBB gp-9 frame here.

That project required a little rework to get the fly wheel to fit into the narrow end of the shell but otherwise it fit just fine.  Now If I could ever get back to those handrails....

The attachment process will be the main issue - it may take a little jury-rigging to derive a method to attach the shell to the frame. Even among Lionel Geeps, they changed the attachment method over the years, and certain modifications are sometimes necessary when swapping shells to get them attached to the frames. For example, MPC and some LTI Geeps had metal tabs on the frame with two screws that attached to the shell, and later Geep versions have plastic moldings in the shell with four screws that go through the frame into the shell.

Thanks for the info. Might wait till after the holidays to try it .

Bob