Here is the part number and applicable model numbers for a Minnkota prop:
MKP-6
PROP NO.:
MOTOR DIA.:
PROP NUT KIT:
#2061125
3-1/4"
A
35A, 35TA, 40TA, 65TA, 35T, 50T, 50MXT, 65T, 555T, 555TA, 565T, 565TA, 30AT, 33AT, 36AT, 36AT/H, 365T, 365TA, 365TMB, 765T, 765MXT, 765MXTA, 865T,
865MXTA, 665T, 665MXT, 30EX, 36EX, RT27/S, RT36/S, RT40/S, RT40/SC, 40PD V2, 36PD/C, 36PD/AP/C, 40PD, 40AP, EDGE 40, EDGE 40/H,
ENDURA 30, ENDURA 34, ENDURA 36, ENDURA 38, ENDURA 40, ENDURA PRO 32, ENDURA PRO 38, 40AT, 40AT/H, MAX 30T, MAX 36T, MAX 40T,
POWERMAX 30, POWERMAX 36, VECTOR 40
According to sneaker's "theory" the thrust rating of the motors is a lie and your boat won't go any faster with a 12V motor if you get the highest thrust rated motor instead of the lowest thrust rated motor.
I wonder why my jon boat is faster with a 55 than it is with a 36? I can tell the difference by the wake it makes and the rate I pass stationary objects. I haven't done a GPS speed comparison, but it doesn't appear to be any reason to do so.