TH400 to 700R4 swap - have questions

[dagen_1]

since buying a used transmission can be a nightmare, i found a 700R4 that needs rebuilt (lost 3rd & 4th) for dirt cheap.

at 60 mph my engine is running at 3k, which i don't like nor does my wallet when it comes to paying for gas.

what would be involved (besides a fresh transmission) to swap out my TH400 for the 700R4?

trans cross member?
drive shaft?
coolant lines?

i have a cluster with the correct gear indicator (PRND thing)

any help/advice/feedback is appreciated.

 

[dagen_1]

i need to add more info:

my truck has a 305. the trans i'm thinking of getting (either for core or rebuild) is from an 89 IROC, dude said it had the H.O. 305. i thought IROCs had 350s..but what do i know

 

[Devs93]

irocs had both well the 3rd gen camaro break down from factory v8s came as ttops 305s non ttop was usually 350 but could have a 305. Also just a thought it could be a good time to upgrade to a 92/94 needle cluster during the swap.

 

[dagen_1]

... Also just a thought it could be a good time to upgrade to a 92/94 needle cluster during the swap.

hmmmmmmmmmmmmmmmmmmmmmmmmmmm ya know... you might be right!


edit: would i need a DRAC if i went with the 700R? (assuming i still have moonie gauges?)

 

[Devs93]

hmmm I think 700 r4 was used till 92 so was moonies so Im gonna say yes. however iirc the 700r4 has the same tailshaft and speed senor they just hook upo diff due to the diff in gauges

 

[DRAGGIN95]

Does your wiring harness have the lockup torque convertor wiring in it, if not you will need a standalone lock up kit such as this, I have installed several and I also personally ran one for 10 year's in my 80 model with no problem's. http://www.jegs.com/i/Painless+Performance+Products/764/60109/10002/-1

 

[outalne94z71]

hmmm I think 700 r4 was used till 92 so was moonies so Im gonna say yes. however iirc the 700r4 has the same tailshaft and speed senor they just hook upo diff due to the diff in gauges

moonies were used till 91, 92-94 needle gauge is a mess to swap over to a 91 and earlier as the plug and wiring is different and need to add the drac but a 91 needle gauge is almost a direct swap to the 88-90 trucks, just a matter of moving 3 wires, swapping moonies in a 91 to a 91 needle cluster is plug and play

 

[outalne94z71]

hmmmmmmmmmmmmmmmmmmmmmmmmmmm ya know... you might be right!


edit: would i need a DRAC if i went with the 700R? (assuming i still have moonie gauges?)

moonie gauges do not use a drac, they have a chip in the cluster itself

if that was my truck i would go 6 speed manual with it, could be a whole lot of fun

 

[Devs93]

he has moonies wants to swap to needles wich isnt plug n play in his truck but talking about gauges isnt gettin the info needed on swapping trans

 

[outalne94z71]

he has moonies wants to swap to needles wich isnt plug n play in his truck but talking about gauges isnt gettin the info needed on swapping trans

he has a 89 so if he found a 91 needle gauge it is 98% plug and play, matter of moving 3 wires

a th400 uses a 32 spline yoke and usually 1350 joints, a 700r4 is 27 spline and usually 1310 or 1330 ujoint so there is another cost along with shortening the shaft for the longer trans