For a while, Amazon parts were a little more easily obtained, but at this point I think they're about the same.
I've owned and driven a PV544, 122 sedan, 122 wagon, 145S, 145E, 2 different 1800e's. And without reservation, I can tell you that the one I have enjoyed driving the most is the PV. I've owned my beater 544 since 1998. It was a bit of a pile when I bought it, parked for 17 years in an open-sided carport. It's a little hard to pin down why I like it so much more than all the other round-fendered pushrod Volvo's I've had. But it was just more enjoyable to drive around even when it still had 90 hp, skinny tires, and a soft suspension that would lean waaaay over in corners. Over the years I've kept tweaking at it, now it has about 175 hp and a pretty good suspension and wide tires - so it's even more fun.
I guess if you're looking to drive an older car like that, you're doing it to get some vintage feels, and the PV simply has a lot more vintage to it than do the newer old Volvos.
Things to look out for:
- rust
- rust
- rust
- rust
- mechanical condition
The mechanical parts on these old things are so easy to fix, and you can get all the parts, I simply wouldn't worry the slightest about one with a million miles on it. But a low mileage one from a salt belt state? Run away. These are simply not economically restorable from rusty shells, probably never will be. Just don't even get into a project like that, regardless of how good a 'deal' it is. SPend the money and make it a road trip to go get one from a dry salt-free state somewhere. money *very* well spent.
PV's are simpler than the Amazons are (and the Amazons are pretty damn simple). They have a simpler body structure, fewer areas for rust to hide out in. One big plus to that is that the PV weighs several hundred pounds less than an Amazon (even a coupe) or an 1800. The downside however, is that they cannot withstand rust as well as those newer overbuilt for safety cars can. On a PV, rust can quickly move to making important parts fall off the car. So if you buy one, get it up on a lift and look underneath carefully.
- Front frame spars - the main arms that stick forward from the firewall to the bumper, the whole front end hangs off that, the rest of the sheetmetal up there is not structural. These can rust at the bumper ends (the bumper falls off, sometime later the steering box or idler arms falls off). They can also rust back at the firewall - and if the bottom part of the arm (that reaches under the front floorboards) rusts the arm can sag 'up'.
- sills - as with any car, but I think they're a bit more structurally significant in a PV since the body is so light.
- floorboards - common to be rusty because of the original rubber floormats (great at keeping dampness underneath them, against the metal) - wouldn't worry *too* much about them though
- rear end of the transmission/driveshaft tunnel - this is an unusually critical part of a PV because of the unusual rear suspension. All 4 control arms (other than the lateral panhard rod) attach to the back end of the tunnel. The lower main arms angle in toward it from near the wheels. And the torque control arms reach straightforward to it from the top of the differential. Significant rust here means that the rear axle falls off. Which is... bad.
- subframe arches over the rear wheels - only notable because the rear springs sit on them - and they can rust out in a way that sends them shooting into the trunk area. I've seen it on rusty old PV's in junkyards here in the salt belt.
- rear-most section of the trunk floor - this is like the floorboards - many cars will rust here - it's not serious. There's just a dropped section of trunk floor, with a rubber mat to hold moisture, and a sometimes leaky trunk lid right above it.
Other than that, like I said, mechanical conditions is practically not worth worrying about unless you're paying *top* dollar and everything is supposed to be sorted already. Interior and paint and all that - all pretty ordinary in prices to do, or not, as your tastes see fit. Interior parts like upholstery, door panels, headliners, etc are all still available.
The older models - 62(?) and older will be 6 volts, unless someone has swapped them. That might be a slight minus. ALong with the 6V cars also cam the B16 (and earlier, the older you go) engines, which are incrementally hard to find parts than the B18 the 63+ cars had (shared with Amazons, 1800's, and in slightly larger size, 140's and 1800E/ES models).
Personally, I like the looks of the 444 models - the ones with the split flat glass windshield. The flat glass just gives it a more authentic vintage look, vs. the slightly anachronistic curved glass on the 544. The 444's also have a much neater looking 'Art Deco' dashboard - vs. the slightly cheaper looking dash the 544 shared with the Amazon. The 444's are just far more rare in the US because, for most of their production, Volvo wasn't officially importing to the US. I think they did in the 444's last year of production, but sales weren't that large then. 544's were imported in much larger numbers.
And for even more cool points, there is the PV wagon version (445 with split flat windshield, 210 in curved/544 version). Even the 210 is rarer than a 444 is, it seems. And the 445's? Probably all brought over one by one by owners, not by the company.