Those are

P34 Paragons used in many applications by Chris Craft I have the same transmissions in my boat the P 300 series is the actual tranny the differences are the gear reduction or lack there of P-34 is a 2.5 to 1 reduction if you see PV in the serial number it means V Drive Here is the rest of the story so to speak

P-31R or L Direct Drive the R and L are for the rotataion
P-32AR or AL 1.5:1
P-33AR or AL 2.0:1 307 Q Motor
P-33R or L 2.0:1 327 Q Motor
P-34BR or BL 2.5:1
P-35 BR or BL 3.0:1
From my Q motor parts manual for what it is worth.
I know for a fact Tim has P-34BR & BL in his Commander with 427 300 hp motors so they are rated much higher than my 235 hp.