lionel shells, do they fit gp's and sd's

The major design changes in the GP or SD shells should be when you have a major number jump, for example a GP-7 to a GP-20, then the shell changes too!

A GP-38 should work with a GP-40.

SD and GP were differant engines, if I am correct the SD has three axles per truck assembly and the GP has two axles per truck, so the shells most likely won't interchange.

Lee F.

I think in MPC Lionelville, they are one in the same for the GP7, 9 & the SD9, 18, & 20.

I have swapped a GP-9 shell onto an SD-9 chassis without any problem. They are the same length. I am pretty sure that the GP-20 and SD-18 bodies are identical, but I don't have them in front of me to compare. A scale SD unit is quite a bit longer than a Geep, but in Lionelville they are the same except for the trucks. 

The one thing to watch out for is that the original postwar Geeps attached the body with two screws, one at each end of the shell, which engaged tabs sticking up from the chassis. Later versions attached the body with screws from the bottom of the chassis. These later bodies have posts molded into the shell that are not present in the postwar Geeps. I am pretty sure that both the SD-18 and the GP-20 used only the later type attachment, but I haven't had one apart in a long time so not 100% certain. 

I've done a lot of swapping shells, mostly putting older shells on more modern TMCC/RailSounds equipped chassis. For the most part, the shells on Postwar and traditional MPC, LTI and even up to present day traditional GPs and SDs are interchangable. This makes it a lot of fun, and quite easy, to swap shells. Lionel's GP-38s are a newer design and use a different chassis. I haven't tried any swaps with these.

As mentioned by Southwest Hiawatha, there were some changes in design of the attachments of chassis and shells. To expand on that somewhat, earlier designs all had screws in the front and rear of the shell going into metal tabs that are part of the chassis. Starting in the nineties, Lionel started attaching shells by using four screws going through the bottom of the chassis and into each corner of the shells. However, the metal tabs were still in place on the chassis, so attaching a newer shell is a simple matter of drilling holes through the front and rear of the shell and driving screws into the tabs.

More recently, the tabs were eliminated from the chassis. Shells continue to be attached to the chassis by the four screws. To swap shells on these most recent chassis, it is necessary to glue plastic pieces in place on the shells above the chassis screw holes, and drill holes in these new plastic pieces for the screws to drive into in order to attach the shell to the chassis. 

For Geeps made during the MPC era, the GP-7's and 9's are easy for the most part.

That said, Mt. Clemens did change the handrails from a fragile (but more realistic)

wire handrail with plastic stantions to the PW style stamped metal rails.

Switching these shells will take a bit more effort, and the handrails are part of the frame. In the case of the wire handrails the plastic stantions are part of the frame, but can be removed.

The GP-20 shell (which was created buy inserting a new  tool into the

GP 7/9 mold) will also take a bit more effort. To create the longer hood for the GP-20, the headlight for the long hood was modified, and uses a "christmas light" type bulb.

If you place a GP-20 shell on a GP 7/9 frame, and leave the 7/9 headlight "as is"

it can melt the top of the GP-20 long hood.

Most of these diagrams are in the files section of the MPC yahoo group.

Ken