700R4 manual or electronic speedo

I've got ane 89 astro that the tranny went out on.
I removed that and installed another. The new trans was not set up for the
electronic speedo sensor, but was set up with the mechanical drive.
Did any of the earlier Astro's or S-10 have mechanical speedo's?
I thought about changing the instrument cluster and running a cable.

Yes some do. But I don't understand wanting to swap to older technology. The need parts should swap from one trans to the other to run the electronic speedo for you.

CD

what involved with that? the "new" trans has a mechanical drive
the old has the large hole for the VSS.

Not sure of all of the details. I think you should be able to swap the tailshaft and the internals and that is all.