I have just unearthed a pair of good N type hood rests and the measurements tally with the P type . The difference being the height at which they are mounted on the body and as the N wheels were 18" but with 4.75" tyres which actually made them greater in diameter than the 4. 0r 4.50x19, It was necessary to scollop out on the top edge to accommodate the wheel and tyre . Therefore these brkts are easily altered to the P type configeration by letting in a segment of metal. Easy Peasy
I am waiting for my camera to charge up and will send pics and measurements later if you are interested