My boat has factory oil temp gauges and the existing senders are at the bottom of the oil pan (cast aluminum pans) Is this a good spot? Also one of them is broken. What ohm range might it be?

what brand are the guages?

The gauges are the stock ones that came
On the boat in 1980. For the life of me I can
not remember what they say on the bezel

Mine are in the pans.

+1 So are mine.

That old scarab.....maybe Nordskog gauges? Stewart warner?

You can take the wire off the sender, and ground it with the key on. See if the gauge pegs to full HOT. If it does, maybe the sender is bad. if it doesnt, check wiring.

The tip of the sender where the wire bolts to broke off, that is why I need a new one

Youll need to find out what brand gauge you have, or take the other sender out and do some ohm readings. Most of the american stuff, is compatible. VDO style, might require a special sender.

here is a picture of my oil temp gauge. it is a 150-300 range. Does anybody know what type of sender I should use with it?

Looks like a old faria or teleflex gauge. I'd think this will work fine

http://www.cpperformance.com/p-13075...si-gauges.aspx

Its the best spot,,,,,the best thing to know is the temp going into the motor