Some 4x4 questions

[davepl]

Is there a physical (ie: fitment, compatibility with transfer case, etc) reason that GM never offered a big block in the K series (4x4) trucks? Or was it just a marketing decision? Or maybe the transfer case couldn't handle the torque?

Also, when buying a 4x4, what are the desirable drivetrain options? Can someone translate these into "12-bolt, 14-bolt, Dana 44, Dana 60, etc?"

No option - what's standard?
F43 - 9000# front axle
F44 - 11000# front axle
F47 - 5000# front axle
F48 - 7000# front axle
F49 - "Heavy Duty" front axle (K20 only)
F54 - 12000# front axle

Thanks,
Dave

[yellow70GMC]

to fit a big block into a 4x4 you either have to "massage" the firewall or move the t-case forward a couple inches. so to put one in you either need custom driveshafts, or firewall modifications, which is why GM never did it from the factory. can't shed any light on the axles, but i'm sure someone else will chime in

[mrein3]

A lot of guys are running big blocks in their 4x4s. Some had to massage the firewall, others did not. One option if you have massage work to do is to install a body lift.

Another issue is exhaust manifolds. Some have had luck with stocker exhaust manifolds from the later 70s with minor trim work to the frame rails and/or the casting humps on the manifolds. Others simply put in headers.

One thing to consider, if you aren't putting in a complete monster of an engine, is a 700r4 transmission. You can get one with an Advanced Adapters output shaft installed so it mates with the transfer case adapter that was behind an original th350. Leave the transfer case where it was from the factory, and move the engine forward the approximate 2 inches or so. This will have you running stock driveshafts which you already have if you have a stock 4x4.

When I re-engined my 4x4 I simply built a 383 and used ALL the stuff I already had. You can make some pretty nice torque and hp numbers with a small block stroker. Nothing like a big block but you also won't have to suffer as bad at the gas pump.

Regarding what to look for - I'd look for a 71 or 72 because they come with disk brakes. I had a 3-speed manual for a few years then swapped it out for a th350. I like the auto WAY better for what I use my truck for but I suffer a tad in gas mileage. If you haul lots of weight or want to push snow I'd look for a 3/4 ton. I use my 1/2 ton to plow snow around my driveway and get by just fine because 1/2 tons of old are way beefier than modern 4x4s.

One guy whom I haven't seen post in a while built his own 72 K30. Most of the parts up to 1987 interchange and by 87 you could get a 1-ton 4x4. WAY beefier axels than stock 1/2 or 3/4 ton but that all comes with a price. The guys who own D60 front axels are pretty proud of them so you will pay dearly for one. Plus then the brake components are gonna cost you way more to purchase and maintain.

[davepl]

I have a heavily built 200R4 that I was using behind a ZZ502; how hard would it be to use one of those (giving me an overdrive gear)? It's the same length as a TH350, but I don't know how a transfer case connects to the transmission.

[CG]

You should check out this area of the board... http://67-72chevytrucks.com/vboard/f...splay.php?f=30 .... Lots of threads on this very subject for ya.

[willett]

err....
which generation are you talking about?

[msgross]

axle guide.. http://coloradok5.com/axleguide.shtml

12 bolt = 1/2 ton GM corporate rear
10 bolt = 1/2 ton or 3/4 corporate front (nearly identical to DANA44)
DANA 60 = 1 ton 4x4 front axle or 3/4 ton GMC rear or populare rear for muscle cars
14 bolt = GM corporate axle in 3/4 and 1 ton trucks (semi-floater or full floater)

Basically the ring gear gets bigger the higher you go. Some have different spline counts etc...

[mrein3]

Originally Posted by davepl

I have a heavily built 200R4 that I was using behind a ZZ502; how hard would it be to use one of those (giving me an overdrive gear)? It's the same length as a TH350, but I don't know how a transfer case connects to the transmission.

I don't know if a part is available to make that transmission work with your transfer case.

A 700r4, minus the tail shaft, has the same bolt pattern as the th350 that is set up for a 4x4. An aftermarket company, Adavnced Adapters, makes an output shaft for the 700r4 that is the correct length and has the correct number of splines so you can simply use it in place of your th350. The overall length is about 2 inches longer so you either have to move the engine forward that amount or move the t-case back and work on the length of your driveshafts.

Guys are running 200-4r's in 2wd applications but I've never heard of one in a 4x4.

[Dooley]

Originally Posted by davepl

Is there a physical (ie: fitment, compatibility with transfer case, etc) reason that GM never offered a big block in the K series (4x4) trucks? Or was it just a marketing decision? Or maybe the transfer case couldn't handle the torque?

Also, when buying a 4x4, what are the desirable drivetrain options? Can someone translate these into "12-bolt, 14-bolt, Dana 44, Dana 60, etc?"

No option - what's standard?
F43 - 9000# front axle
F44 - 11000# front axle
F47 - 5000# front axle
F48 - 7000# front axle
F49 - "Heavy Duty" front axle (K20 only)
F54 - 12000# front axle

Thanks,
Dave

They started offering the 454 in K30 trucks in 1982.