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rich weyand · 03-18-2015, 05:51 PM

All of what you say is true EXCEPT you don't need to know what is in the transfer case. Those parts are a bear to find!

I just wanted to know what adapter was on there already so you could get one adapter that would be that adapter corrected by 1.3 (30/23 or 60/47). With no adapter on there, all I needed was the actual and indicated speeds.

So you need a step-up adapter. 30/23 is 1.304, 60/47 is 1.276. Closest fit is 1.300, for which there are three: GM #3950350, GM #1565719, GM #368026. Not sure why there would be three, though my parts book covers 6 model years.

All that said, I can't find any of them on the net.

Closest I can find is "speed up 28%" aftermarket ratio adapter here:
http://www.transmissioncenter.net/sp...n_______va.htm

Anybody else know where to get a 1.300 output adapter?

03-18-2015, 05:51 PM	#23
rich weyand Registered User Join Date: Apr 2014 Location: Bloomington Indiana Posts: 1,041	Re: speedo ratio adapter parts. All of what you say is true EXCEPT you don't need to know what is in the transfer case. Those parts are a bear to find! I just wanted to know what adapter was on there already so you could get one adapter that would be that adapter corrected by 1.3 (30/23 or 60/47). With no adapter on there, all I needed was the actual and indicated speeds. So you need a step-up adapter. 30/23 is 1.304, 60/47 is 1.276. Closest fit is 1.300, for which there are three: GM #3950350, GM #1565719, GM #368026. Not sure why there would be three, though my parts book covers 6 model years. All that said, I can't find any of them on the net. Closest I can find is "speed up 28%" aftermarket ratio adapter here: http://www.transmissioncenter.net/sp...n_______va.htm Anybody else know where to get a 1.300 output adapter? __________________ Rich Weyand 1978 K10 RCSB DD.