Suggest you "search" for a better forum..ie. one that deals specifically with "yesterday's tractors"...How old is your 350? The IH 50's/60's stuff used separate hyd and trans lubes/fluids. The trans drains (may be two of them) will be under the diff. and under the trans....for the hyd. "block", follow the hyd lines from the pump (usually found right under the distributor), back to the block...there should be a large "bolt" head (about 1 1/16") on the opposite side of block..that's where the fill hold is...trans fluid should be 80w-90 gear oil...hyd fluid can be 20w hyd fluid. BobG in VA