In theory you might be able to find a trooper 88 to 91 with a 4 cylinder and an automatic and it would bolt up to the LUV motor. I'm not sure if you could get a flex plate that would match up to a torque converter for that trans and you might have to do some custom driveline work, but enough would bolt together that it might work.
I think I'd just go ahead and swap the motor or swap the LUV over to an Auto trans Trooper frame. With all the little iffy stuff here and there swapping just the trans, sounds like more work and less pay off than going for more of a conversion. But, that is just my opinion.
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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)
MEPR: Man, my 4x4 makes all other LUVs look good