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factorystock · 01-01-2011, 07:48 PM

I agree with Bob B. These auxilary transmissions were found in big rigs and 10 wheel dump trucks in the 60's for heavy duty on and off road work.Not generally found in smaller light duty trucks. Is there a data plate rivited to the side of trans? Your really need this plate to figure out what you have. Spicers came in the 6000 series 7000 series and 8000 series. For example Spicer 6041 : 1st 2.14 2nd 1.24 3rd 1.00 4th .86 or Spicer 6041-A : 1st 2.14 2nd 1.24 3rd 1.00 4th .75 So the 6041 has a .86 overdrive and the 6041-A has a .75 overdrive. Other series have similar ratios, just more heavy dutier the higher the series.

01-01-2011, 07:48 PM	#9
factorystock Registered User Join Date: Feb 2007 Location: west coast Posts: 3,400	Re: Question about a 67 GMC 4speed with aux trans (twin stick) I agree with Bob B. These auxilary transmissions were found in big rigs and 10 wheel dump trucks in the 60's for heavy duty on and off road work.Not generally found in smaller light duty trucks. Is there a data plate rivited to the side of trans? Your really need this plate to figure out what you have. Spicers came in the 6000 series 7000 series and 8000 series. For example Spicer 6041 : 1st 2.14 2nd 1.24 3rd 1.00 4th .86 or Spicer 6041-A : 1st 2.14 2nd 1.24 3rd 1.00 4th .75 So the 6041 has a .86 overdrive and the 6041-A has a .75 overdrive. Other series have similar ratios, just more heavy dutier the higher the series.