If I was going to pull a 5th wheel trailer over 10k-14k range with a older high mileage gas truck it would be a 8.1 GM 2500/3500 SRW or a F250/350 SRW Ford with the V-10.
Now if that 35' trailer weighs over 14k lbs I would look at the DRW trucks in those two brands.
Without any weights we have no idea what size truck would match up with a xxxx brand 35RL trailer.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides