I40 does get into some pretty good grades once you hit NM...
Flagstaff down into the Phoenix area on I17 has some pretty good down grades getting off the mountain where Flagstaff is setting...
I17 also has a couple of high wind side drafts going through a couple of canyon cross winds...
You might want to head down to I20 to I10 in TEXAS for the final leg into AZ and totally miss all of the high country roads... KY down to I40 probably in the Nashville area would be best to miss all of the high mountains East of of Nashville... I40 East of Nashville has some pretty high mountains too...
Nashville to Little Rock should be fine on 140. Then at Little Rock I would start heading down to pick up I20 that will dump you into I10 in West Texas then on into AZ.
I10 will have hazards if you stop over night along I10 where it is very close to the border state. You may want to sleep with one eye open - lots of foot traffic during the nights... You also may have to deal with Border Patrol traffic check points...
Of course I have no idea where you want to be to going in AZ... Just figured it would be the Phoenix area...
Just remember from Little Rock on West all of the towns start getting farther between each other making it more difficult in case of breakdowns on your older truck...
Getting towed off the Interstate is also a very hugh bill for your Insurance Company... Check your coverages...
Roy Ken
