M101 fuel tank use

[neverfinished]

Hi guys. Since my tank has numerous pinholes I pulled the tank out of one of my trailers and it looks almost identical except that it's plastic and the sending unit hole is in a different location. I was wondering if any of you have used one of these tanks and if so did you just put the sending unit in the existing hole and not worry about it being under the access panel in the bed floor? Also,any suggestions on what kind of material to use for gaskets around the pickup/sender units? Thanks.
Ted