Question and advice needed from those experienced in tranny swaps on RRC:

The valve body in my 1993 SWB RRC 3.9L seems to have seized the reverse gear. Didn't stay up on fluid/filter change and got swap water in the trans during deep washes (4'+ sandy water). Anyhow, got all forward gears going but reverse only half shifts into reverse now and slips, not engaging. on filter change there was 1/2 teaspoon of clutch matter in the pan - fluid was not burnt -- just milky. drain and refilled 3x. changed filter second time. put in lucas and seafoam.

So, I found a used 1993 LWB 4.2L trans and had it delivered to the house. haven't changed it out yet. My repair logic and options currently are:

1. remove, clean, and reinstall the current valve body. no concern, other than the waste of another $20 of tranny fluid and time. will have to do a drive-way tranny swap so I'm inclined to give her another "FIX' attempt to avoid the pain of a 4wd transfer/tranny/etc remove/reinstall.
2. swap the valve body from the 4.2 trans to the trans on the 3.9L (original one) in the truck. concern -- possible gunk still in the circuits, different part number from rover.
3. swap out the trans entirely without fooling with the other valve body. Concern -- are the SWB and LWB ratios different OR is the computer different?

thanks,
TD
Melbourne, FL
space coast