I am wanting to replace the 4spd transmission in my 78 242 (B21a) with a 4+ o/d unit from an 80 245 (B21a) or an 86 245 (B230f).

My 242 is a solid running brick, but I find highway cruising is just tooo much of a "flight of the bummblebee."

A few questions for the board...

Do I need to have a custom drive shaft built? - or will the front shaft from the 86 compensate for the shorter space b/w the rear of the o/d unit and the rear diff??

What might I expect in the drop in final drive ratio??

(My Haynes manual is too general to provide such data.)

Any other information, experiences, or thoughts are most welcome...

Thanks in advance