1995 G20 Chevvy Van - no temp reading

Discouraging Sunday. Bought universal guaranteed fit NAPA mechanical temp gauge kit. Opened up doghouse, drilled firewall, and.....
bushings don't fit! &)(*&)&*. Put it all back together, and still no gauge reading.
Possible wrong sensor (sender)? It has one wire. Seems to be 3/8" pipe thread, located on left side of engine. NAPA's rig had 1/2" fitting. NAPA's setup requires use of bushing that has shoulder inside to stop sensor from slipping completely inside.
What should the cold resistance be for the sensor? Is it possible the sender/sensor was wrongfully replaced a couple of years ago - never worked....... Are the sensors different between 305 and 350?
I believe engine is 305, not 350. Door plate says it's a G21-305
Appreciate any help - don't want to remove doghouse again without a fix!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.