Aftermarket temperature gauge/oil leak

[bldrbiodiesel]

Hi guys, I have an after market temperature gauge that is wired into the fuse box. The problem is that when I turn on the fan the temperature jumps up about 20 degrees. I know this is interference but, I would like it to read accurately, where should I wire it.
My truck has never leaked oil until recently (after my last oil change) then it developed a small drip from the back of the oil pan (maybe). I just had my 5 spd. rebuilt and got it back on Monday, they said the rear main seal was not leaking and that maybe it was the turbo mount. The problem is that since I got it back it is leaking really bad! Any thoughts? Thanks, Mike

[Calvin1958]

There are lots of places it can leak from up top.Check up top because it's probably coming down the back of the block and running down from the drain hole at the back of the valley.Good Luck,Calvin