Tac hook up?

Were is the tachometer hook up on my 1988 chevy s 10?

Tachometer hook up on my 1988 s ten 2.8 tbi is were?

The only place to get this is the ignition coil connections. There are three connections to the coil, one is for the secondary lead for spark and the other two are main connections. The two white wires are tach leads to either the distributor or back to the PCM. lots of times there's a splice connector close to this area that doesn't have anything connected to it. This is intended for diagnosis of the ignition system but is a perfect place to get a tach signal from. If you have the connector use it, but if you do not all you must do is splice to one of the wires and you'll have your tach signal. Good luck.

I was a GM mechanic for many years.

It is the white wire on the ignition coil. If it ever had a tach, there's a white wire off the coil that goes to a small metal can about an inch long. This is a filter for the radio. If it has one, hook up to the white coming out of it not the other side where the white wire goes to the coil.