Going OverDrive

[69fleetside]

Ok,I have a 350/th400/3.73-12 bolt. But I want to take out the th400 and replace it with a 700r4. Can someone tell me what i would need to make the transition go smoothly(as far as having what i needed in the way of parts/special tools). I would like to put a one-piece driveshaft in,but I don`t know where to buy one,or if a stock one-piece would match-up to the 700r4.
Can I use the 2 piece driveshaft I have now,and will it need modifying(other than a tranny yoke).Does the linkage matchup with what i have? Would I be better of buying a new crossmember? Is it much trouble to mount a speedo-meter cable? I just don`t want to get stuck somewhere and not finish as soon as I possibly can. Have any of you made this kind of switch and could you please give me some tips..........please

 

[resurrected_jimmy]

this is a 2wd truck?

 

[69fleetside]

yes..........2wd

 

[1979jimmy350]

the shifters are in the same postion, is this a 2wd or 4wd? if its a 4wd you will need to mess around with the tcase to get it to work. The cross member should work but you will need to change it's postion. Does the 700 you are using have speedo gear or a reluctor ring?

 

[69fleetside]

2wd.........don`t know if there is a gear or ring(for speedo-cable), i`m planning on ordering the
tranny from jegs(TCI) and they don`t specify.

 

[resurrected_jimmy]

should be a fairly easy swap and jeg's may supply the tranny in both speedo configurations. As already mentioned the crossmember will have to be relocated but will work. I'm not sure if the yoke on your current driveshat will work but swaping to the correct yoke for a 700R4 and shortening the drive shaft would be the only other things I can think of that would get in your way. drivelineman is a vendor in this forum may be able to help you with Q's about this part of the swap

 

[1979jimmy350]

i belive that the yolk is the same, i know the 350 and 400 had the same yolk and the 700 has the same as the 350

 

[BadBob]

The 350 and 400 definitely do not have the same yolk. The th350 and 700R4 do though.