Some other info on input shaft lengths:

http://board.marlincrawler.com/index.php?board=16;action=display;threadid=2804

Also, if your intent is to mate the Toyota R series tranny to the Isuzu 3.2/3.5, you'd probably be better off using the late Tacoma R150F and the Isuzu AR-5 bellhousing. I think that would take care of any input shaft length issues. The Dakota bellhousing would fit, BUT, it probably would have to be cut out for starter clearance (the starter is on the opposite side). The Isuzu bell would be better and you'd just have to re-use the stock set up.

Greg