Newer transmission in an older truck

[americanengineer]

I've put a 1992 Silverado 5-speed manual transmission into my 1964 C10 and it works like a dream. It has an electronic output but I want to use my original mechanical speedometer. I think the transmission is identifed as NV3500.  Does anyone know if that transmission ever came fitted with a mechanical speedo output? It seems like GM first put it in trucks in 1988, so my guess is that it probably had a mechanical output then. I think the transmission may have also been identified as a HM290. 

[Mikebtte]

I am pretty sure you have to use the $300 black box that converts the signal from digital to mechanical.  Or you can get a replacement gauge that looks factory and has digital abilities. 

[americanengineer]

Thanks, those are good suggestions and are my fall back position, but thought I'd check around to see if I could keep it closer to original if possible. By the way, my best friend growing up had a 58 Apache as his first vehicle in the early 70's, and I always wanted one, love those dual headlights.

[Mikebtte]

2 hours ago, americanengineer said:

Thanks, those are good suggestions and are my fall back position, but thought I'd check around to see if I could keep it closer to original if possible. By the way, my best friend growing up had a 58 Apache as his first vehicle in the early 70's, and I always wanted one, love those dual headlights.

Nice! I put a 4l60e in my 59 Apache but ended up using the newer gauges. Was unable to justify the cost to make it machanical.