Yes, they are a good idea every 30-50kmi. At least in my opinion. However, you can do basically the same job using automatic transmission fluid in the oil. Just pour in a half bottle, let the engine just warm up, and proceed with your oil change and double filter change. This is what I do whenever I purchase another vehicle.
50km? That's what I drive in a day between home and work... Here we usually do oilchanges every 6000miles (10.000km). When I do the oil and filter change I'll use the cleaning thing.
My father has a the same engine as your truck. He started with .060" and the engine had a little shutter to it like it missed, but when I hooked up my scanner to it there were no misses recorded. He regapped them and now he says "Its not gone, but its way less often.
My engine runs pretty fine tho. Sometimes I think it shudders while rolling at 50-55mph while giving it a little to no gas, I could imagine it it's kind of hard to tell since my shocks are shot and it rides pretty rough.
Well a few other good things to do would be changing the differential oils. The front has likely never been changed, and is usually the one that will absorb the most water since it is not used often (yes, in the snow it is, but it must get the oil warm enough and long enough for the water to evaporate). Changing the rear requires the rear cover to be removed, and it will give you an opportunity to inspect the insides. Use brake cleaner to clean out the nasty in it.
I've been thinking about doing this too, I'd like to get a new rear diff cover along with making it all nice under there so oil in rear diff is on the list, I totaly forgot about the front tho, thanks!
I wouldn't do more than 2.5" on a 350. Even my 454 with could not utilize a full 3" of exhaust.
That's what I've heard too, I have dual 2.5" and headers on my Impala with a 383 and it sounds/works great.
Yes, make sure you have someone available to tune it that knows what they're doing before swapping in a 0411. At least you have the 350, there is less to modify in the tune to make it suit your needs. You will need a "CASE" relearn dome by a dealership or tuner, but they have to follow specific directions. I had 3 dealerships (one twice) say "we can't do this for you, everything we've tried doesn't work" but a mom and pop shop was able to perform the relearn for me. I got a load of misfires after I installed mine, but apparently the 0411 is more sensitive to picking those up and I ended up having a bad distributor gear. Just keep that in mind
I think they are out of 01+ Chevy trucks and vans, and Lextech is the one you need to talk to in order to get a wiring diagram for your truck so you can plug it in. He also sells a kit with connectors, and the conversion took me 6hrs or so but I made sure to take my time and make it look professional.
Not sure how much a 0412 is going to cost you over there, but here from a junkyard its probably $30, but no guarantee that it works ya know.
This actually sounded a lot more difficult than I thought and after looking at the junkyards there is only one in the country, costs about $350 and that is only the box no wires or anything.
I'll start with a proper tune up and maintenance and go from there. Thanks for all the tips and help!