i dont really know how to post a thread this might be it.

anyways i have an 85 sr5 efi manual on 37"s and all the other junk...my transmission runs great no complaints about it.. but when in reverse there is a loud knock that it makes thats consistent every time im in reverse. its been going on for a few years and theres no loss of power, ive still wheeled with it, pulled plenty of friends out of being stuck all in reverse with no loss of power what so ever! I know its coming from the trans by getting it on jack stands and running it in reverse, getting under and listening to it
all the yota gurus i talk to are stumped so finally i decided to turn to the internet..... any ideas????
sorry if this has been asked ive looked a ton and have not found