Since you don't need Overdrive you may want to look at a C5, 3-speed with torque converter lockup, but not controlled by computer
It was used on/with the 2.8l engine in 4x4 Rangers, 2.8l/2.9l and 4.0l used same bell housing patterns
But 2.9ls/4.0ls all got the A4LD thru 1994
But there is a length issue in that A4LD and C5 are different lengths, same transfer case can be used but drive lines may need to be changed
Your current computer would turn on the CEL because the 2 A4LD trans solenoids are missing
The A4LD is not a bad automatic, most of the internals were used 1986 thru 2011 in Rangers and Explorers
Article here on A4LD with some tips:
https://www.therangerstation.com/tech_library/a4ld.shtml
And there are several other A4LD "rebuild diaries" where people have used 5R parts that are more heavy duty like the OD drum since it was used more in the 5R for 2nd gear