Numbered oil temp gauge replacement question

So I ordered the numbered oil temp gauge for my early car and am replacing this eve. The first thing I notice is the new gauge uses a three spade plug that is unlabeled. My old gauge has three separate female spade connectors and each plug is labeled. I figured out which one is negative but what about the other two?

Anybody have a clue?

Second thing I notice is the plug on the new gauge sits right where the retaining bracket for early cars lays across the back of the gauge housing . What this means, is there is no way to secure the housing in the dash using the old bracket as is. Do I need to cut the old bracket and punt?

Just a bit frustrated cuz it was pretty much explained as a plug n play replacement.

Joe, are your gauges held in by brackets with studs and nuts, or do they just press in with rubber rings to hold them snugly? I can't remember when Porsche made the change.

I think the change to rubber rings was introduced on the 1970 / C series cars, so the 69s were the last to use the studs.

Oh yeah, 69 had the retaining bracket and nuts. Here's the prob.

Uh-oh. Looks like you should try a rubber ring type gauge, or maybe just a rubber ring on your gauge. Will it work in a 69? I don't know.

Tom,

I got the rubber ring for my tach & clock but they nned to be trimmed and stick out like a sore thumb. I think the 70 openings are a bit bigger. Anyway, I got my dremel out and notched the strap so it now fits. Lets hope I can read the diagram I made with which wires went were. :eek: