'89 module on driver's side transmission tail shaft

What is this?

1989 chevy suburban 1500, 2wd. 5.7.

I don't have a manual specific enough to tell me. The module is located on the tailshaft of the transmission...driver's side. There is a hose...assuming vacuum...that goes through the firewall wall behind the brake booster.

This darn thing is leaking transmission fluid and I'm trying to indentify it.

Thanks

Mdl

Speedometer cable?

You will need a new seal on the speedometer gear to stop leak and sometimes the plastic speedometer gear gets a grove in it,