According to my book the 1720 was first made in 1987. Here are the values
1720,2wd,new price 9120, average trade in 2530, hi trade in 3640, average retail 5570, hi retail 6270.
1720,4wd, new price 10984, average trade in 2820, high trade in 4060, average retail 6210, high retail 7000
These have Shibaura engines, 3 cylinder, 12forward, 4 reverse, 23.88 pto hp