Okay, I suggested the 4L60, not the 4L60E
You did, but the 4L60 has essentially no advantage whatsoever above the 700 because they're mechanically identical. A 4L60 (non-E)
is a 700R4, they just changed the name and nothing else.
Like the other 2, the 4L60e is also trash until you put over $1k into it in parts alone at the very least, and that's before getting into using expensive mechanical diodes or the $1k Sonnax valve body. You can easily drop $5k on a 4L65E build if you're not careful, especially if you don't have a core.
Sadly, if you don't spend big bucks it often doesn't matter who rebuilds it because it's never going to last half as long as the factory unit did, which is expected to be at least 100k miles but often makes it just past 125k before failing. Unless you know someone who's extremely familiar with the valve bodies, knows the 200 minor changes in flow paths and parts over the course of 20+ years, and is willing to put together a unit comprised of parts spanning even longer since some good stuff is in the '04^ models. You'll want
this case,
that valve body design, the hardened shaft from
these models, the
later 5 pinion planetary, put
this rebuild kit into
that pump, etc.. Certain clutch materials are pointless and some are detrimental, different shift kits achieve the same result in different ways and not all mods are compatible.
Rebuilding these things correctly to handle any amount of power or to last 100k miles or more takes waayy more skill than most "rebuilders" I've had the displeasure of speaking to could even imagine. In my experience over 90% of them are nothing more than parts replacers.
The 200 has a cult following in the Turbo Buick world and therefore has infinite support for high power builds as well as testimonies to their durability even in stock form.
I'm no transmission expert myself, I've just grenaded a dozen 700s and researched the ever-loving snot out of the subject for years in an effort to stop doing that. Mostly because I only want to go through the pain once for my truck. It's taken me over a year to even find a builder I want to trust because I've been burned by half the shops around.
OP: Swap it to a manual if you truly want it to last- it'll cost the same in the end. If you do stick with an auto please don't even think of buying a cheap torque converter.
