[AZKen]

The manual I have, and was quoted by David, says Kick Panel or pillar. It is a X-6023 printed in 1961 I believe. You could deduce if they said that, they were going to put them either/or. It says it replaces a X-6003. Wonder what it says? If X-6003 is the first manual for 1960, and it says either/or, and I have an original 1960 with holes in the pillar, it may mean they were giving themselves options for different factories/tag suppliers or cabs were punched with those holes for 1960 Chevy. It seems that on the WIKIweb, all Chevy's had pillar. Depends on what X-6003 say somewhat. Interesting, at any rate. I think 55-59 GMC was a wide tag and the hinge pillar was wide so they mounted them there. I think I've learned what David said, there always seems to be an original exception. Quality control, specific procedures were a little lax back then. Maybe X-6003 says kick panel only. It has a print date of 1959.
Don't know if poster serial is high or not, our data says 95,000 V6's in 1960. Also Jmclendon shows chart with 15 as 1/2T is that not 3/4T? His "B" rating is 6000-10,000. Decoder hiccup?