Question: My concern is the locking differential (G80) that GM has on its '05 pickup trucks. I am told this is based on an Eaton Locker and is very rugged. However, there is no external engagement mechanism, meaning you have to spin one wheel over 70 rpm for it to engage, I am told. It would automatically disengage when both wheels are speed matched, forcing a repeat of the engagement process at the next "stuck." I would rather engage my driving wheels to prevent getting stuck. And what if I tried doing a few donuts on dry pavement? I would appreciate your comment on this unit. Also, what do you think of adding a mechanism to manually engage/disengage the unit? Has any "kit" been developed for this purpose?
Answer: I couldn't agree more with your assessment of the GM locking differential. I have a Chevy pickup with the optional differential and was convinced by a couple of GM engineers that the new model would work great. Well, my opinion is that I totally wasted my money on this option. Oh, wouldn't it be nice if there was some aftermarket kit that allowed us to modify the present rearend and just pull a cable for a positive lockup?
For a replacement, it depends on what rearend you have in your truck, as you didn't say which model you had. If it is the big AAM rearend, then you are pretty much out of luck. That is, until some time next summer when Tractech will release its Truetrac limited-slip unit for it.
Now from my understanding, there has been a shortage of the AAM axles, so your truck may have what is referred to as a 14-bolt. Or, if you have a 1/2-ton pickup, you may even have a 10-bolt rearend. If this is the case, then there is both a Truetrac and a Detroit Locker available. For a selectable locker, there are ARB Air Lockers also available for these last two rearends.
Question: My current (and first) project involves an '82 K-20. It came from the factory with a 6.2L diesel, a TH400, an NP208, and 10- and 14-bolt axles. To me, that's the perfect drivetrain with the exception of the engine, front axle, and transfer case. I have an NP205 and a Dana 60 to put under it. Now, for the good stuff-the 454 bored 0.040 over with a few more modifications. It came out of a '90 C-3500 (which is in my backyard), so I have everything I need. The motor is computer controlled with TBI and so on, so would I have to use the same-type distributor, or could I use one with a vacuum advance?
I'm gonna make this work because I know I can do it, but my dad says it's not possible and it's a dumb idea. The truck is not gonna be street-driven so I don't have to worry about inspection. All I need is for you guys to tell me it can be done, and that would make me feel so cool because you guys are the coolest.
Answer: What a great project for a 19-year-old. I am impressed with what you have planned and getting a complete donor truck was a great idea, one I always suggest when doing a project such as this. Keep in mind that you will need a different adapter between the transmission and transfer case, as the one from the 208 will not work.
My suggestion is that you take your time and do everything right the first time. If in doubt about something, ask questions, lots of questions, and most likely you will get different answers. Not that any of them are wrong, but consider the source and the application before you do the same thing to your truck. But also don't think that you have to have all the trick parts and pieces right away. Pay attention to the safety features and make sure they are right. Don't overcam or overcarb! This is one of the biggest mistakes most people make.
I am a bit confused as to your question about the distributor, but this is an answer to what I think that you're asking. You must use the electronic distributor with the throttle-body injection. The control box (computer) advances and retards the timing as needed. No, you cannot use a vacuum-can-type distributor with the EFI system, and no, you cannot use the electronic distributor with a carburetor fuel system. Either one is interchangeable within the engine blocks when using the matching intake manifold.
Hey, make it street legal! Half the fun of owning something like that is being able to cruise with it and show it off. Be sure to control the urge to display "the speed and power" part. Tickets are tough at your age-well, actually, tough on anyone when it comes to insurance rates. You will know what it is capable of, so you really don't have to prove it. Besides, big-block power can even break Dana 60s and 14-bolt axles. Most important of all: Have fun building it.