Super T10 vs M20/M21

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Shields

Full Access Member
Joined
Apr 9, 2016
Posts
55
Reaction score
52
Location
Kelowna
First Name
Dayton
Truck Year
1976
Truck Model
C10
Engine Size
383
Hello Everyone, here’s the update:

The Super T10 has a speedometer port bore like an M21 or TH350 at 0.875. I did not order the $80 B&M part as I was looking at 2-4 week lead times to get one to Canada, instead I spent $20 and ordered this no-name aluminum one from Amazon. I went to go install it and only then did I realize my ST10 still had the speedo bullet installed (I swore it was missing). So I took the time to measure the speedo bullet and the plug from Amazon. The speedo bullet diameter was around 0.860, the speedo block off plug diameter was around 0.850. It would’ve been nice to see the port plug a little larger but I went ahead and installed the plug with the new O-ring and it was a nice snug fit, I don’t see it leaking anytime soon.

Thanks to everyone for the advice, cheers.
 

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