Desert Ryder

I'd like to upgrade the derailleurs on this bike.
I'd like to start with the rear first. It has the original Shimano Acera RD. Would an LX or XT rear derailleur be compatible with the brake/shifter combo?
Same for the front, though it isn't that big a priority as I spend most time grinding in the top ring.

Ultimately I'd prefer to go retro with friction thumb shifters and separate brake levers.

pics for reference:

veganbikes

I wouldn't put much money into this bike, just get it functional till you can get the bike you want. It is a lower end bike with cheaper components. It was originally $380 brand new you could easily spend that in parts for this bike to "upgrade" it and it will still be a low cost aluminum frame with a low travel cheap coil fork that was designed to hit more of a price point. If the bike is basically functional ride into the ground with minimal parts and labor to keep it safe to ride. In 2008 7 speed was still almost 20 years old and 10 speed road had been out for several years and 9 speed was the higher end stuff for MTB with it first coming out in 1997 for XTR and 10 speed XTR hitting in 2010. The newest Acera was 8 speed in 2008.

The components would work as 9 speed and below will generally all work together road and mountain but again not worth putting nice components on this bike as it is a basic aluminum frame nothing high end from Trek. Still serviceable still rideable but there are so many other worthier candidates to put nicer parts on. Plenty of neat more modern frames and also tons of good used stuff with decent frames. If you are really into aluminum look into the Specialized Duralcan which was ridden by people like Ned Overend and currently loved by bike aficionado Ronnie Romance. Otherwise look for a nice steel frame that doesn't use Hi-ten steel and put stuff into that.

Friction shifting is great, and XT is awesome but put on a more deserving bike and use this as a beater.

Desert Ryder

Thanks for the input.
So, the answer is yes for compatibility.
That's all I really needed to know.

I can find the rear LX or XT RD pretty cheap on the bay site, Under $30 shipped. There are upgrade RS suspension forks for sale all the time around here, $100 and less. Not really necessary for most of my riding on this bike.
The thumb shifters can get more pricey for a clean set but usable ones are available in the $30ish range. But again, they are just a desire, not a necessity.

None of these parts are an immediate concern. Just thinking out loud and thinking about the ease of setting up/maintaining a friction system over the index system of shifting.

For more serious DH riding I have a vintage GT STS DH.

Desert Ryder

I thought about this....I'm doing it backwards.

Since there is actually nothing wrong with the current components, I could just buy a set of friction thumb shifters add a set of brake levers, and ride the wheels off it.
Since they don't need to be higher end I can find everything for literally under $30. No more dialing in the SIS system, Low maintenance and I can feather the shifters if need be.
I guess I was being nostalgic about the XT parts and wanted what I had way back when.

Since I originally only paid $20 for the bike it keeps with the bargain bike theme

veganbikes

If you want XT get a bike with XT nothing wrong with that, I have done that a few times (or put XT on the frames because I bought them as frames) No need to put any more money then needed to keep it functional enough till you can get that XT bike you want. With quality indexed shifting I really don't have to do much maintenance at all. My 9 speed XTR shifter with an 8 Speed XT RD running 1x9 on a bike I abuse (though not mountain biking) requires very little maintenance outside of basic stuff you would do with any bike regularly. I haven't had to do anything since I built it really. I have replaced a cable and housing but I would do that with friction once and while.