Long term mopar guy here, we have a '74 Challenger and a '68 Barracuda but I'm looking to buy a '77 power wagon. It's a 318 and looks solid and stock from the photo's.
Just here asking as to what are the usual points to look for when buying ? Also I believe these are full time 4 x 4, can you get aftermarket hublock kits for these ?
TIA

Rust is the biggest problem. Over the windshield, floors, bed cross members. Most mechanical parts are available, body and interior not so much.

There used to be kits to install locking hubs and convert the transfer case to part time. But those went out of production years ago. No matter, yhe stock stuff is fine until you get to giant tires. There's work arounds but you'll be changing axles to do them. The transfer case was used in trucks up to 1 tons, it's not weak.

Those above pretty much covered it. I would add, to not expect great gas mileage. The trucks weigh in between 4600- 4800 lbs, expect 10 mpg, 12 is considered really good (I got 14 mpg 2 times, back to back on a 100 mile trip to and from.I have no idea how that happened), could be 8 mpg (or less) if its used mostly for short trips. The lock out hubs don't seem to make much difference in the mpg, barely noticeable.
Of course, your experience may be different then mine, I've only had about 10 of them over the years.

also look very close at the steering box mounting area of the frame for cracks.
that was a problem area when those trucks were relatively new, and i repaired several in that area.
back then, rust wasn't a problem as these trucks were "new", but age and weather over the years since can change things dramatically.

Some of the 1970's trucks had issues with the amp meter. Those can overheat and cause problems. There are ways to rewire it to solve the issue. Maybe someone else can recall which years were affected.

Depending on how you are using the truck, the full time 4x4 can be an advantage. Around here, the roads are often hilly with many turns. It's common to find some patches of snow and ice mixed with bare asphalt in other places. In this environment, a full time 4x4 works very well. In my opinion, the best transfer case has a 4x2 selection, a full time 4x4 and part time 4x4. This means all of the bases are covered. Unfortunately, transfer cases like this are uncommon. I don't believe Dodge ever used a transfer case like this in the 72 to 93 trucks. In these trucks, you have to decide between full time or part time 4 wheel drive. The good thing is that both options are available.

Trucks that came from the factory with rubber floor mats instead of carpet seem to rust out faster in a humid climate. The floor covering traps the moisture which lead to the floor rusting from the inside out. If you can, check both sides of the floors before purchasing the truck.

In my experience, sure grip axles were not a common option in these trucks. It was available, but it seems like most buyers did not order it. There were a variety of axle ratios available. The axle ratio has a significant affect on what the truck can tow, haul and how it drives.Trucks with the 4.10 axles do not cruise real comfortably at 70+ mph. These gears are great for towing though!

Overall, these were solid, well built vehicles. Assuming the one you are considering has been well maintained and NOT abused, it should provide you with good service. Unfortunately,some owners abuse trucks, so inspect it carefully.

Thanks for the reply's. I'll likely buy the thing, I'm actually over in the UK and these are pretty rare here. The owner has sent a few pics over and it looks OK from the 'photo's but obviously I'll have a real good look at the vehicle before committing. It's priced at around $10K which is slightly under the average, there are another 2 for sale here in the uk, both are over $15k.
Thanks again for the reply's

Re ammeter, trucks prior to 81 all had a full power ammeter. As noted they were problematic but usually due to loose connections.

A shunt wire from the alternator to the starter relay is recommended.

The truck in question almost certainly has the full time case. The case isn't the problem in these, the front wheel bearings are. Maintenance is often neglected and oversized tires make it worse.

The amp meters back then didn't use a shunt. Meaning all power went threw the bulkhead disconnect and to the meter in the dash. I kept the stock design just upgraded it a bit. You may find this helpful.

Unfortunately I lucked out and the truck sold last night, it was bought by a guy who was undecided then decided yes. But thanks guys for the replies, I'll keep a lookout for something similar. I'll be back

Sorry to hear you missed out on it. One will come your way soon.

Thanks, there is another. But it's twice the price and looks far too good to used as a working vehicle