I have a slew of gauges I picked up from a local truck wrecker. They all came out of a Freightliner highway tractor and Im pretty sure are made by Isspro. They are about 2 1/16" diam and fit my pillar quad pod with minimal filing to enlarge the holes slightly. I have been using the autometer 2258 sending units and so far they are all workin great! So far I have Eng. oil, tranny, diff (all AM2258's), boost (mech.), water temp (AM2385), and pyro (stole the probe when I got the gauge)...all these gauges were $10 each, some wreckers sell em for $5 each. The senders cost me about $12 each, so I got all rigged up for pretty cheap...still got more gauges to install later when I get around to making my custom dash...
Im just gonna have to figure out (hopefully with some help here) how to make a Freightliner speedo work in this mess. Cable to elec? Dont really have a clue to how its gonna happen...