2-cable 904 trans swap

[RookhavenJeff]

I have a 63 Plymouth Valiant with the original pushbutton 2-cable shifter on a 318/904LA.I have a few problems with the transmission:

1. Parking lock sprag is stuck in neutral. Even with the cable disconnected, the sprag is locked in. (wouldnt be bad if my e-brake worked)
2. The shifter cable hole in the case is too large for the o-ring to seal, creating one heck of a mess.

I like the idea of the original pushbutton selector, but this transmission hates me and has vowed to never let my car see pavement again. I am ready to swap it out for the easier fix and sell it.:banghead:
Sooooo my question is :
What all is involved in swapping over to a newer 904 automatic with a floor shifter from, say, Jegs or Summit?
I have aftermarket throttle and kickdown cables on it as the original engine was a /6. Also, the trans has the flange-style yoke that bolts to the driveshaft.

 

[rapidtransitric]

an a 904 later version should be an easy swap. get the converter with the trans bolt up to your trans mount. after market shifters are pretty easy just follow the instructions. and if you can get the drive shaft with the trans for the slip yoke you will probably have to have the drivshaft cut to size and rewelded and balanced

 

[VDART]

problems-- if the motor is a 63 it has the small register crank--- custom converter can be made.
need new slip joint drive-shaft
linkages to connect the tranny

this has to be remedied to swap a newer style tranny--- or go with a 1966 version -- it has the slip yoke style with a small register converter.
I do have 1 from a 1966 dart slant car-- been sitting in covered storage for some time .
Lawrence

 

[RookhavenJeff]

Would prefer to just swap it out with a new one (warranty). I've had a couple bad run-ins with rebuilds in the area, which is probably why my parking lock wont lock.

So, if I get a new trans, why would my current converter not work? I think the motor is a 68 model.

 

[cudamark]

If your engine has a '68 or newer crank, the '68 and newer torque converters will work fine. As for the problems with your existing trans, fixing the park cable and/or linkage shouldn't be a problem. Pull the small cover where the cable attaches and see if all the parts are there and working. You should be able to get a slightly oversize "o"-ring and some RTV to fix the shift cable leak. If the case is ruined, all bets are off but I'd give it a try before I went to all the trouble of a conversion.

 

[38 Dodge]

If you make this transmission swap I would be interested in the cables.

 

[RookhavenJeff]

After an extended park in the driveway, the Valiant is getting a new 904 next week. With the new style slip yokes, how do i measure how much to have the driveshaft cut down? Is it a simple measurement from the rear-end u-joint to the new slip yoke u-joint?
I will have my pushbutton selector, cables, and trans up for sale very soon. Also have a couple sets of factory manifolds for LA-V8 and some odds/ends things.

 

[green1]

Car on ground; measure from rear flange to end of output tailshaft(the splined one). Give that to driveshaft guy.