700R4 died!

[josh86k10]

Well, after 218K miles, the last 20K of which have been on 37's, my 700R finally died. I was just driving down the road at ~50 mph when all of a sudden my motor red-lined and I lost power to the ground. Pulled over, all looked good, but when I pulled back on the road I had to rev up to ~4500RPM just to get moving, the same thing in all gears. Since it had 218K on it and I was 2 miles from home, I said to he** with it and drove it home like that, slipping the whole way home.

So here's my question, should I put another 700R back in or find a TH400? I have found a military TH400, adapter, 208, converter, and front driveshaft for $400 5 miles from my house. Is this an easy swap? Is it a good deal? I don't care about overdrive anymore, haven't used it much since the boggers anyway. Can I make my stock column shifter work? Is a TH400 the same length as a 700R? What is a TH400's 1st gear ratio? Thanks in advance.

Oh yeah, as of now it has a 305, 700R4, 208, 60/14FF, 6 inch lift, and stock length driveshafts (the front has some slop in the slip joint also). Truck is a short bed.

 

[beater_k20]

what gears are you running? and what size tires?

 

[josh86k10]

4.56r&p and 37x13x15 boggers.

 

[1979jimmy350]

if you go to a 400 you will have less of a first gear ratioo and will lose over drive. If you do a lot of highway driving you might want to stick with the 700

 

[76R4JIMMY]

having 37" tires and 4:56 you cant beat the first gear for an auto - tranny

 

[josh86k10]

All right, I've been using the little search button and I have learned a few things. So, I'll post what I think I've learned and ya'll correct me if I'm wrong.
My 86 K10 started life with 305, 700R4, NP208, and I've swapped in D60/ 14FF w/ 6" lift and stock length driveshafts.
I have found a TH400 (with converter, adapter, 32 spline 208, and a front driveshaft and rear slip yoke for good measure) from a military CUCV.
So here's what I think I've learned:
-only 3/8" length difference in TH400 (shorter) and 700R so driveshafts will still work
-stock crossmember will still work
-computer wires to 700R4 can just be disconnected and tied out of the way
-need to run vacuum to TH400 from intake manifold
-need to purchase and install electric kickdown switch on gas pedal, should already have stuff to bolt it up stock
-stock column shifter will work (indicator will be off though)
-stock lines will work
-stock flex plate will work
If any of the above is not correct please let me know. Also if all of the above IS correct let me know. Thanks to everyone on this site, especially those that have posted and those that I have dug up your old posts.

 

[big83chevy4x4]

the overall length of the 700r4-208 and th400-208 is the same length. i don't think there is a 3/8" difference.

the rest looks correct to me.

 

[josh86k10]

Thank you.

 

[pauly383]

You can pirate the indicator from a junkyard truck , and then it will line up . Or just model paint black over everything from n to the right , and paint d-2-1 on it