thank you for all the suggestions 3b. i have been working on this off and on for days now and have got NOWHERE! i have about 7 things that are too much for me to figure out and i rotate between them. today, i am am almost ready to reach for the BFH!
i ended up removing part of the bed to test the sending unit. this involved drilling out rivits and taking out a ton of bolts. well when i did it looks like the sending unit is working it has about 2 volts when plugged in and when i unplugged it it shot up to 5 volts at the wire. so then i decided to switch out the dash to another one i had. plugged the new dash's gage in and after i grounded the dash the gage seemed to work! then i installed it and switched over the wiring and NOTHING!
now the pink wire has 12 volts and everything else is dead. the brown wire side, the plug in on the fuse box, the sending unit- all dead. i don't know if i fried something messing around with it all so much or what. i have read the sending unit and gage are match voltage sets, but i don't remember for sure what the tank/sending unit was for, i think 64 to 66- it has been several years back. so i don't know where this leaves me. maybe take a electronics class and buy all new stuff. heck this wiring is a little wicky in this thing maybe i should buy a new harness- all for a truck i rarly drive and can't sell sounds like another great idea- ha ha.