Can you tee off the oil sending unit to run an oil pressure gauge and keep the idiot light working? on a 440

Thanks Tom RR

Yes.

Yes. On BBs you can use the 2nd port for that galley that's always plugged. Look about 1.5" to the passenger side from the existing sender.

I've had to do that more than once when using spray bar valve covers, works good

i've done it on all engines except a second generation 426 hemi. [never had one of those to work on]
a T fitting works good. i prefer to use brass fittings instead of steel or iron plumbing stuff.
you can also use stainless as well if you prefer, and can source those.
as an aside, i use a good quality teflon paste sealer, such as Loctite brand 567.

Yes you can use the second one that is always plugged, but I believe it is a larger thread size and will likely need a reducer.

I found it's easier jut to use a "T"

Either way will work.