Resolved Tremec TR3550 shifter base to transmission bolt size

I'm trying to get together all the bolts needed to get the TR3550 installed in the car and I'm missing a couple of the shifter bolts. I don't have the transmission here so I'm not able to pull one out to measure, and the only information I could find online was for a T5. The Hurst shifter instructions mention 5/16" bolts, but nothing more. The T5 are metric M8x1.25x20mm. Anyone know off hand what size bolts I need to order?

Follow up.

I was able to get to the transmission and pull an existing bolt.

For future reference, the shifter base bolt for a TR3550 with a PRO-5.0 shifter is 5/16"-18 x 1", you will need a quantity of 6.