[padgett]

Even GM says in the Service Manual: if in doubt use a mechanical gauge. Factory instrument senders are notorious for inaccuracy and failing.

I have several TSBs warning of faulty oil pressure senders in particular. Back in the day I used to keep a couple of senders on the shelf just for when not if.

Also none of the senders are one-size-fits-all, are many different gauges and gauge/switch combos just in A-bodies.

ps when in doubt check. It is possible to "fix" a dash gauge to read anything desired.