The RoadMaster wagon idea has merit, but instead of the gas-pig V-8, why not bolt in a 6.5 turbodiesel along with your T56? Peninsular Diesel makes a mechanically injected turbo 6.5 that uses the much more robust Hummer blocks. In a station wagon. It should give 300,000+ miles of trouble-free service and won?t be an electronic nightmare to mate to the manual. Another engine option (although probably not available at this time) is the 3.0 V-6 diesel that comes in Sprinter vans. In either case get the biggest radiator you can stuff into the vehicle. Cooling is a Chevy weak spot. The Cummins 4BT3.9 is probably too tall to fit under the RoadMaster/Caprice hood. The 6.5 or 6.2 is a bolt-up.

The 4BT3.9 in a 4x2 Suburban makes good sense if mated to a stick. Back in the 80s, Chevy made a 4x2 ?Burb with a 6.2 NA engine and 2.73 gearing that was allegedly good for over 30 MPG EPA rating. The ?Burb has a deeper engine compartment and can accommodate the upright inline engine.

You can also get a rebuilt five-cylinder Sprinter diesel for a bout $4500 with all the electronics and wiring harness. It may be (like the Cummins) too tall for the RoadMaster but will fit the ?Burb A-OK.

In either case, if you are converting a gas vehicle to a diesel, pull all the interior upholstery out and have the vehicle Ziebarted inside and out. Ziebart material (cutback asphalt) is outstanding sound dampener. Then put Brown Bread (another commercial sound deadener) sheet on the inside of the firewall. That will kill the diesel noise.

Both these vehicles are available with the GM ten-bolt axle. The ten-bolt gives you an awesome range of aftermarket gear ratios: all the way from 2.47 to 4.88 and higher.

Depending on your base vehicle, you are looking at a $8,000-$15,000 project plus the cost of the base vehicle.

I need room for 6-8 people. I've heard mixed reports about the GM fwd vans. I've had good luck with gm cars. The main problem is prices, used vans are up in my area.

I found another diesel option. Cummins b3.3t. It weighs only 560lbs with 85hp and 215tq. Not enough power for the suburban. There's a 16 page thread on dieseltruckresource. He gets 27-35mpg with a 4wd jeep swapped with a b3.3t. He's running completely stock jeep trans,tcase, axles, gears,etc. He's also making over 100hp and 300tq with minor mods. The engine is a bosch VE pump which is completely mechanical and cake to tune. A new engine runs about $4k.

I think I could do the 4bt burb for 7k. Less if I used a 5 speed. With the 4bt I can use ford or dodge transmissions.

The chevy astro comes with room for 8. My mother gets 19mpg mixed and she's a gassaver nightmare. I was able to squeeze 30mpg out of a short highway trip. I think I could average 25mpg highway. The downside is the aero is horrible, handling is dumpy, and the front seats have annoying foot wells. My mother got 230k out of her 1988 and has 206k on her 2000. Both very reliable. She replaced the 88 because only the sliding door worked, and it suffered from lots of electrical problems. The 00 has been through several sets of door handles already as well as a radiator, water pump, ABS servos, several serpentine tensioners, arm rest, and a fuel pump.

I guess the new Mazda5 is out of it, not enough used ones around. It's a 6 seater with 2 rear benches for 2 ppl each. I haven't actually seen a 3 seater bench you can comfortably get 2 child or booster seats on plus anyone sitting between them, so I guess you can figure on getting the same number of kids in it..... unless you have faith in 3 wide meaning that and wanna get a K car or old Pontiac 6000 and try and cram 3 wide in front and rear benches.

Damn my parents had it easy, did the school run with 6 kids in the back seat and 2 sharing the front passenger seat... that's what's causing pollution and crowded roads, seatbelt and child seat laws. Needs 3x as many cars to move 8 kids these days.

If that's in a Cherokee, mewantmewantmewant.

At the risk of getting bashed, I'd suggest you get a mini-van, over a wagon. When your kids are younger, the wagon is Ok, up to a quantity point. However, when they get to about 12, they start sprouting and the increased leg room is a huge help.

I've got a 98 Chrysler Town & Country, with the 3.8L engine and I've been very pleased with it. We paid $3500 for it, with about 90,000 on it and it's up to about 116,000. After I finally got the power steering pully fitted properly, we haven't had any issues with it. We retired a 94, at about 189,000, largely because the 98 became available.

One thing well worth noting, if you can get something with bucket seats, instead of the benches, do it. They reduce a lot of squabbling, which can get really old on long trips.

The astro... Great vans reliable. Mine always averaged about 19-20, about 70city-30highway. Well that was till the speedo stopped working. My van has about 170k and I've only had to replace 1 door handle, alt, water pump, and the differential (because dealer didnt flush rear end lube....)

FWD Vans. My mom had a 98 olds silhoute van. It got like 30 something mpg whenever it was really driven. One trip it got 40, that was on a scout trip going 55 or less the entire trip.
Sadly the engine died at a little under 80k miles, in 2007. The coolant was flushed improperly by a shop (switched to a small shop after what happened with astro). There were lots of airbubles in the coolant....

So I would say if you work on your own cars, either choice is a great choice. Parts are "cheap" for both.

Get a volvo
 

I'm a little late into this thread, but I'm surprised nobody chimed in with a turbo volvo. Our two cars right now are a '01 Saturn SL, and a '97 Volvo 850R. Picked up the Volvo for $3000. It's approaching 200k miles now, and still does 0-60 in just over 6 seconds. Supposedly it tops out at 155, but I've never verified that. I know it'll pull from 65 to 115 pretty damn hard, and it still wants more at 115. I get 28-30mpg on the hwy, only about 18 in town. All stock. You can get them with seating for 7, and it's as easy to work on as the Saturn. Easier in some cases.

Gotta go with the wagon on this one - I love wagons and I've always been a fan of the Roadmaster/Impala/Fleetwood/Vista Cruiser group. I've looked off and on at Roadmasters and Fleetwoods myself and they seem to be nice and cheap as you said. Plus the LT/1 is basically the cop-spec motor, itself a somewhat toned down version from what the Vettes were using.

FWIW, my Mom had an '04 Sienna...junk. Second least reliable vehicle we've had. She got rid of it at 24k miles and never looked back. With all wheel drive, only averaged ~17-18mpg, too.

Wagons are great if you're going small, like a corolla or Escort/Tracer. Roadmaster? I had a 9C1 Caprice... fuel & maintenance pig, its redeeming values being great speed and handling. Sold it for a Tracer Wagon that I like better, and which is sufficient for two small kids.

I've been impressed by MoPar vans. Very nice drivers. Maintain them carefully, and they'd be good. I'm leery of GM stuff, but that's more a prejudice than experience.

As far as swapping motors around goes... bad idea, unless you've done it a few times and know what you're getting into, and want the work. Fuggetaboutit!

Try finding one of those old toyota vans. I hear they are decent and RWD

https://www.toyotavanpeople.com/
https://www.yotavans.org/

you can probably get them pretty cheap.