I'm thinking there is a thickness difference & I saved an article in the Jan 1999 "high performance mopar" magazine regarding using thinner frictions to use 6 clutches in a 5 clutch 3rd speed (their words) drum from a 75-79 360 eng. 10 second drag raced 904 based '66 valiant. I have one to do & I am going to Google it.

live every 24 hour block of time like it's your last day on earth