Don't have a 99 but an 00. Pretty much the same coach, same front cap, etc. but the 00 offered the 2 slide and ISC350 engine late in the yr. The coach @ should be in the low 116--- or high 115---.
Don't know what size you're looking at but the larger 99s,00s & some 01s were part of the NonRecall/Recall tire offer. Original tires were 275/70/22.5 which were not near enough tire for the load. Monaco and Goodyear changed out the tires to 295/80/22.5 to carry the same load at much lower inflation pressure. If the coach has these bigger tires you're in good shape although they're now 4 yrs. old.
Basicly the 99Windsor was the same as a 97Dynasty. In 97 or 98 they changed the roof from rubber to a 1 piece fiberglass and moved the genny up front.
Hope this helps.
Dave, Miss Sue and Lucy the Scotty
00 Windsor, 40', Grand Cherokee Limited