727 lockup on a 3.9l?

I have a 1994 B150 van with a 3.9l v6, and I'm wondering if I can replace the A904 lockup transmission with a 727 lockup for more durability. Are the bell housings the same?

Thanks

Both use the same bellhousing. The 904 with lockup is electronically controled. The 727 with lockup is either centrifugal (engine speed) or hyraulically (wheel speed). These were only used in the late 70's and early 80's. Both are 3spd that were replaced with 4spd. OD transmission. This was the A-500 which was based on the lighter 904 transmission. In 1990 the A-518 (based on the 727) was introduced and a few years latter the lockup converter came about. (The OD and lockup converter are electronically controlled in these transmissions.)
(Belongs in van sub-forum.)

The transmission I have is only a 3 speed lockup. I'm concerned putting in a 4 speed would probably lug the 3.9l with the existing rear end ratio.

Would it be best to try and find one of these older 3 speed lockup 727's you mention? I suppose if I put in an A518 I could just use it in the 3rd gear quadrant. These transmissions do lockup in 3rd, don't they?

The OD and lockup are both electrically controlled by 2 seperate internal solenoids. (The gear quardrant is the same: P,R,N,D,2,1)
FYI: The 518 was later called the 46rh.
Also there are low and highstall converters for most transmissions. The dust shield, converter and engine-trans. braces are different between the 727 and 904 transmissions.

So I could use a 518, put a switch on the dash to allow or disable OD. The bellhousing bolt pattern is the same though? I can always fabricate the bracing brackets if necessary, or find some at a wreckers if they exist. Are the starters the same, or does the 512 use a different starter bolt configuration?

I went and found a bellhousing from an old gutted 727 and it bolted up perfectly, and the starter fits dead on. Even the bellhousing to engine block support bracket lined up perfectly. Do I need to get a 318 flexplate, or will the 727 converter bolt onto the 3.9l flexplate?

I've installed a 727 3 speed lockup, and everything seems fine except for a few minor issues. It seems I have to shorten the throttle valve cable adjustment enough that it doesn't allow the throttle to be opened completely wide open (almost), otherwise it upshifts at too low a speed. Does this sound like line pressure adjustment is required? The other problem is the 2 to 3 upshift, it seems like the lockup clutch engages immediately when it shifts into 3rd gear, and the engine seems to lug a little at light throttle upshifts. This lockup is hydraulic control, no solenoids involved.

One other thing possibly related is it has considerable slippage after sitting overnight when first started. After about 2 minutes it's fine and drives normally. I didn't install the check valve in the cooler hose, so I'm assuming this is the torque converter needing to refill. Does it usually take that long to refill?

Moved to B-Van forum for better reponses!

Start it up in neutral as the fluid doesn't circulate thru the convertor in park.
I don't think there is a shift kit for the lock-up 727 trans, but trango and superior kits will remedy the non circulaton in park problem.
There is another way that I dealt with this problem on a 46rh transmission, I used a regulator made by sonnax parts that allows fluid to circulate in park. (I'm not sure if it's applicable to the 727 lock-up but should be as it will work in a 727 of 46rh which has lockup.)