I have a lead on a 56 4-door where the frame is already restored. Will the body from my 2-door hardtop mount right up?

 

A tiny bit more information would help. Are both cars 88s or both 98s? If so, then most likely yes. But the 88s have a wheelbase of 122 inches while the 98s have 126, so I'm guessing entire bodies would not necessarily interchange between the two. I'm sure the '50s guys will know for sure.

 

from what research I've done as long as they are both 88's or 98's frames are the same.

 

Yes, both are 88s. Sounds like good news! Thank you!

 

In 1956 Oldsmobile produced seven different frame varieties. Here's what their parts book shows with the part numbers:
88 & S88 (2 & 4 door sedans & Holiday coupe) 567304
88 & S88 (Holiday sedan) 567305
S88 (convertible) 567306
98 (Holiday coupe) 567307
98 (Holiday sedan) 567308
98 (convertible) 567309
98 94 door sedan) 567310
As has been mentioned, the 98s had a longer wheelbase than the 88s. The convertibles usually had boxed side rails for extra rigidity. I don't know the difference(s) between the first two.

 

Good info. If that's true I should be ok as I'm trying to mix and match an 88 4-door sedan with an 88 holiday coupe. Thank you!

 

Related question. I'm not sure if I'm supposed to start a new thread or not but here it goes.

When I'm done swapping running gears on my '56 88 2-door coupe I'll have a really nice rust free 4-door sedan roller, no motor or transmission. It's already been epoxy primed and partially painted. The interior I'm told is original and in good condition with no rips or tears. What would this be worth to sell so I can get back part of my investment?