School me on torque/stall converters
42RH/A-500 is a A904 with O/D, 'R' is rear wheel drive, 'H' Stands for hydraulic control. No computer control on pre '96. Found in 87-95 Dakotas. It's $3000 for a GV, or $500-1000 for a 42RH rebuilt, depending on if you want to tackle it yourself. The catch is you need to do a little cuttin' and weldin'. No floor pan mods though, which is good.
Here is the swap info, which is also the sticky at the top of this forum:
http://www.forabodiesonly.com/mopar/showthread.php?t=178459
and the 727 version, A-518:
http://www.cuda-challenger.com/cc/index.php?topic=84774.0
Between the links I've sent, you should have a pretty good bead on things...
Enjoy!