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68 TT · 12-01-2009, 10:01 AM

I don't know what kind of signal the L31 vortec PCM is looking for from the VSS but on the LT1 & TPI swaps I have done they both worked perfectly using a dual output VSS from a 93 vintage Caprice cop car. VSS-231 at NAPA if I remember right.

It has both the mechanical speedo output and the VSS output on it so I was able to keep the stock cable driven speedometer but still give the ECM/PCM what it needed too. The mechanical side was to drive a speedo cable driven radar gun. I know it is the wrong type of signal for a TBI swap but since the L31 is port EFI I figured it might work with it too.

The same VSS unit fits into a 4L60, 700R4 and a T-400.

12-01-2009, 10:01 AM	#9
68 TT Still plays with trucks Join Date: Jul 2009 Location: Spokane, WA Posts: 3,570	Re: electronic speedo? I don't know what kind of signal the L31 vortec PCM is looking for from the VSS but on the LT1 & TPI swaps I have done they both worked perfectly using a dual output VSS from a 93 vintage Caprice cop car. VSS-231 at NAPA if I remember right. It has both the mechanical speedo output and the VSS output on it so I was able to keep the stock cable driven speedometer but still give the ECM/PCM what it needed too. The mechanical side was to drive a speedo cable driven radar gun. I know it is the wrong type of signal for a TBI swap but since the L31 is port EFI I figured it might work with it too. The same VSS unit fits into a 4L60, 700R4 and a T-400. __________________ 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been https://67-72chevytrucks.com/vboard/...d.php?t=484426 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E Last edited by 68 TT; 12-01-2009 at 12:54 PM.