Dyno# locked-V-unlocked?
It can be as much as 50rwhp or as little as 20rwhp, it really depends on the converter stall speed, converter size and converter STR. You should have had it locked on the dyno to really find out, anything else is just a guess.
https://ls1tech.com/forums/dynamometer-results-comparisons/812730-affects-unlocked-stall.html
This is on a Fbody with alot less HP, but too much stall for the combo.
We usually see in the neighborhood of 30-35 HP with a well matched stall, locked vs unlocked, behind motors in the 500 rwhp range.
