th400 to 700r4 transmission swap in 1980 c10 frame

[56hotrodred]

So all this talk of rear transmission crossmember in my 1980 frame has got me thinking about my upcoming transmission swap.

The 1980 frame with 1956 body and my mock up used a side mounted 283/350 and th400 transmission.

My transmission guy is recommending 700r4 which he will rebuild and upgrade to put behind a gm ramjet 350. So far I am agreeing with him on this choice!

First question is can I use my stock th400 transmission mount with the 700r4 and simply relocate it as the length is different?

I like the look of the stock transmission mount as it bolts on one side of the frame. This might assist in reducing frame flex! This is opposed to using an aftermarket crossmember that simply bolts to bottom flange of frame!

Second any difference in physical size of transmissions? Will it fit under cab?

Any other thoughts on my transmission swap plans that I should be thinking about?

[mr48chev]

Here you go. info on all of them. http://www.tciauto.com/tc/trans-dim/

Open the link and it is pretty self explanatory. click on the trans of choice and scroll the page a bit and you see the measurements down further on the sheet. then click the other trans and get it's measurements and that should give you what you need.
On my screen the measurements were highlighted in yellow at the bottom of the page and I had to scroll the page to see them.

[56hotrodred]

Hey thanks. That info is very helpful. Looks like 700r4 is shorter and the trany mount holes are spaced differently!

After reading up a bit this morning I went out and looked closer at the original transmission cross member and noticed another set of holes in the frame to move it forward. I tried it in the forward position and measured a difference of just over 6 inches. Too much to be exactly what I need but it would not be that hard to drill new holes wherever they were required.

Is this making sense to anyone?

[56hotrodred]

After moving the rear transmission mount ahead 6 inches and looking at the link that mr48chev provided I think I am on the right track.

Having just gained 6 inches forward maybe I can slide the engine and the shorter 700r4 transmission ahead the full 6 inches and gain that inch between the firewall and distributor.

I have a short waterpump going on the front of the ramjet 350 with new US Radiator. Last mockup with engine and cab in the frame had tons of room for electric fan set up.

Sounds and looks good on paper but I guess I won't really know until I get the engine and transmission in with the cab also on. Then put the rad in and see what's left.

Does this make any sense to anyone?

Are those Dirty Dingo sliding motor mounts any good to gain that inch forward?