seats

I know this isnt the part of the forum for this but I cant quite figure where to get information i need on seats and interchange. None of the discussions on the 521 truck section on this site appear to be current so i'm hesitant to start a new discussion where it appears no one reads those sections.  Here goes, I need a seat for my 72 521 and have access to a seat from a 75 620.  the question is will the 75 620 seat fit the 72 521.  I checked general info avail on a google search and the seat appears to be close to the same dimensions but the mounting method may be different. I checked fitment of d21 seat and while it fits, the dimensions are different so the headrest doesnt line up with the centerline of the steering wheel and the cutout for the shifter is wider which moves the sitting position toward the door and off center with the steering wheel.  any info appreciated

Thanks

DH