I have a 79 K5 that currently has a 350/th350/203 combo. i am in the middle of swapping in a 454, and would like to put either a th400 or an sm465 with it. obviously, the 400 would be the easiest, but I kinda like the idea of having the the extra low gear of the 465. My question is....if I went with a 4spd, would I have a lot of problems in mud, with mud and water or whatever else, getting inside the bellhousing? Does anyone else run this set-up in mud, and have any problems with it? It won't be used strictly for mud, but a little of everything. Also, if I go 4spd, would hydro or mechanical be best? Thanks for any advice you can give.