The other day my transmission started growling. The growl would increase with the RPMs and not with the vehicle speed. I changed out the transmission fluid and found tons of fine metal powder in the fluid. I'm guessing I somehow managed to chip a tooth on a gear. So I've a couple of questions.

1) The manual says to use 5w-30 motor oil and not gear or transmission oil. Can that actually be right?

2) I'm planning on swapping out the transmission with a used one while I rebuild my current one. What other Isuzu vehicles share the same transmission as my '89 2wd Amigo?

Thanks