The factory parts book shows the same shock absorber "front and rear" for an FC-170. (Not true for an FC-150.) The parts book shows three different diameter bores and part numbers for an FC-170.
The Napa Shock Absorber part number, front or rear, is RR 94008.
The Rock Auto Part Number for a Monroe-Matic Plus is 31000 front ($15.01), and 32207 ($15.73) for rear. The part number for a Monroe Gas-Matic for the rear is 59017 ($30.79). Other listings on Rock Auto show 31000 front and rear.