Backwards swap-replacing an A500 with A904?

[don-vee]

I know, it sounds like I'm ***-backwards. Thing is, my boss has a 95 Dodge van with a bad A500. He's had the trans replaced 4 times, and with 180k miles, he's tired of it and bought a new work van. So, he basically offered up this van to me for nothing.
Now, I have an A904 out of my old 84 van which was rebuilt before a plow truck backed into it. Hard. I parted it out and scrapped it.
So, you see where I'm going with this. I have a good running 95 with a crap A500, and a fresh A904, and I'm looking to marry the two as cheaply as possible. This is a shitty work van, nothing more. I'm not interested in spending the money to buy another A500, so no sense in suggesting that route. The pick-a-part yards around here don't have any A500s, and the cheapest boneyard price I got was $500. No thanks, the van's not worth it. But, the cheap yards all have 904-equipped vans. Lots of parts if I need them.
So, what would I need to do? Do the 904s and 500s use the same flexplates, crossmembers, shift linkages, driveshafts, etc? What parts would I need to get to make this happen?

 

[mtandrews]

the 904 trans mount point is 1 1/4 inch shorter than the OD unit(crossmember relocation needed), plus the 904 body is 6 1/2 inches shorter (longer D/S needed). Higher engine RPMs at road speed which translates into increased fuel consumption and engine wear. I don't know if the linkage is the same. The flexplate is going to depend on whether your combo is internal or externally balanced...

 

[dodge freak]

A longer driveshaft is way cheaper than rebuilding the od trans. As for fuel mileage, yeah it go up but the trans if build right will last longer.

 

[don-vee]

That's what I was thinking. I was looking around on Craigslist a few months ago for a work van for cheap (under $800 or so), and I ran across so many of the later Dodge vans that said, "runs great, just needs a transmission!" so it became obvious to me that these OD units just aren't built like the old 727s and 904s. I'm not concerned with mileage too much, it's just being used locally. As for the balancing, I'll have to check. The 904 I'm using came from a 318-equipped vehicle, so I guess it would be internally-balanced. I also have access to a 727 from an '85 van with a 360, so that's another possibility.
I can do some fab work for the mount, and there's a place near me that does custom driveshafts for not a whole lot. Unless, of course, someone knows of a factory driveshaft out of something else that would work?

 

[pishta]

The 85 360/727 has a externally balanced convertor, the 904 is neutral balance so it would be closer to a bolt in. The 5.2 Mag thats in a 95 is also externally balanced so take your pick. I would lean to the 904 and a longer driveshaft.