Stop in for a cup of coffee

dukeboy_318 said
Can that be used on aftermarket Sun tachs? the polara has a 6 inch, very nice Sun Tach from the 1970s in it but I don't know if it works or not(yet)

Don't know right off hand, depends on current draw. Most of these boxes have low wattage resistors. Here's one on ebay for $36 that would prob suffice for a quick meter test.
Elenco RS-400 Resistor Substitution Box | eBay