I would like this thread to be a good, solid, clean database for any 88-91 LN3 owner to get some more spunk out of their car and know all they should know so that no mistakes are made.

Please add any ideas that you know are available and fully compatible with these engines. Please keep your post neat, to the point and with minimal chit chat.

Before performing any mods. Do be sure that the vehicle has been fully tuned up.

Recommended tune up list:
Spark Plugs (NGK TR55/Delco/Autolite)
Spark Wires (Belden/Autolite Pro/Delco Spark Wires)
Air filter (K&N (Covered Below))
PCV Valve (Purolator, etc)
Oil Change (Mobil 1/Pennzoil Platinum and Purolator PureONE or Delco filter)
Clean MAF sensor (clean with rubbing alcohol and qtip very gently)
Run SeaFoam through engine.
Please add any items if necessary.

Specifically looking for information on the following:
(Who, when, where, how, pricing and capability)
THM440T4 Performance Rebuild/Buildup
Stroking
Cross compatible parts/upgrades between engine generations (such as coil swap already mentioned, what part on a newer 3800 is fully compatible with and can help performance/longevity of the LN3)
Brake Upgrades
Any and all information/links to L67 swap information

I will continue to add to this list as information becomes available.

I believe the Yella Terra Series I cams and roller rockers for the 92 should work for the LN3.

I was scrolling around the club, and found this site: http://www.technicalevolution.com/clunk440.htm

This explains how to fix the 2-1 downshift clunk in the 440T4 transmissions, It is a simple Gm replacement part(a spring). Seems like something I am interested in as I know the bad feel of a 440T4 2-1 downshift. The GM part number is at the bottom of the page.

How about a heavy clunk for upshift? I wonder if that would work for that as well. Some 440 owners might know what I mean, say you're in town, just got off the gas, coasting down, usually about 25 ish, doesn't require any power at that speed, and then it feels like it DROPS into 3rd.

Well downshifts are harder on the transmission than upshifts correct? So it is possible that not just the downshift will be better but possibly up-shifts?, I havn't experienced what you explain, but I know in my car coming to a stop sign when it downshifts to first with your foot off the throttle you can really feel it. Seeing as this is a GM part and fix for our transmissions it should work well.

which is funny, because i feel absolutely NOTHING when downshifting on no throttle, i see the tach jump just slightly and thats it, extremely soft, never any harshness, but the upshift on no throttle from 2nd to 3rd is a nasty clunk, under throttle its fine tho

it'* not a nasty clunk just going 2-1 coming up to a stop sign under gramma driving conditions but you can hear it a wee bit and deffinately feel it. my 1-2-3-4 up shifts and 4-3-2 downshifts are all nice and smooth, you don't even feel any of these shifts in my car at all. When it upshifts the tach falls super smooth and whether im into the throttle on the shifts or off it, there still beautiful shifts. The 2 of us should try this on our cars to see if it fixes these individual problems. If it does work for my symptoms and your'* then we may have another possible good mod for our old rides!

Edit to say: has anyone tried a solid front trans mount on these older cars?