I just bought a 87 TRX 350 and need to change fluids, no clue what weight goes in the engine, front and rear axels, ect.....no online maunal i can find, so any info would be appreciated,

Thanks
Tony D.
94 Honda TX200
87 Honda TRX350

The engine oil is the gear oil ,I think.

I also have a 87 trx350 my manual says to use 4 stroke oil sae 10w-40 and differential oil is gear oil sae 80

I hope this is a misprint. The engine oil is totally different than the gear oil.

use a 15w40 in the engine - or a 10w40 if you are in a cold area
For the diffs use a normal 80/90 gear oil
DON'T use a slippery (molybdenum) oil in engine - a normal mineralis fine and change every 100 hours