Winne Turbo Diesel or other V10 gas model???

I think in the length that you are looking in it depends on the individual MH. Over 36 ft I would go with a DP. Under 34 its a toss up. One thing to keep in mind is that gas MH will have the same eng whether its a 28ft or 38 ft. DP's might have 500 hp in a 40 ft but only 300 in a 34 ft. So in general a short 362 HP gas MH that weights 15,000 lbs will have better performance than a 300 hp DP that weighs 25,000 lbs. The shorter DP's tend to have lighter front ends and many on here post that there are handling problems with some of these. Some report that 34 ft handles ok. From my searching for short DP's the only one that I found was the CC Allure or Intrigue that come with 330 HP that folks report handle well, there may be others and maybe some will post about them.

No matter the power plant, the coach itself will probably wear out first. However, its also likely that a diesel pusher was built better to start with (and on the flip side, a high end gas coach can be built better than an entry diesel coach)

An older diesel should be running just fine. However, even "minor" problems like a failed lift pump can cost many thousands to fix if tis not caught early and it wipes out the injection pump.

Also, that era was before the big jump in power levels in diesel coaches. Well, gas too but you can buy a newer 365 hp V10 for the same price as a '99 diesel pusher which may only have 220-250 HP.

First, welcome to the forum. 34 foot seems to be a good length for a diesel, but other will disagree. With no records, You could take to a diesel service facility for an engine, trans, and 3rd member evaluation. They could also have them evaluate the braking system and steering. The house systems will be the same as any RV. If you like the floor plan, go for it.

It's 34'.

How long is the DP?

Mileage and overall condition for the price would be key factors for me. Diesel? Possibly a Cummins? Diesels are 500K mile motors so other than oil and filter changes they should go on for a long time. Gas motors especially in a MH might get 150K before requiring overhaul.