How hard/ best way to change the thermostat?

Suggestions

On mine I took the throttle body bolts out, and propped the thing on something(screwdriver) and that opened those damn bolts right up.

So is there a way I can do it without taking the plenum off?

YEP
13mm wrenches box & open
13mm fared line wrench
13mm deep & short socket
3/8" ratchet
extension various lengths
swivel joint
patience, cool shade
Pool for the back after ya bent over for couple hours.
OH
Get a Hawaiian Island Babe for a back rub after you take dip in the Pacific at Sunset!
IF you have those tools, you can get it off easiest.
Not fun, tho BUT can be done.
Watch out when ya replace.
Aluminum ya know.
LET THE SEALANT CURE A FEW MOMENTS (Go take break and have brew, it's downhill), before you join pieces.

Kewl, thanks....

And I'm definatly down with the brew and babe.

Thats how I changed mine (Karl's way) . I think its the best way . Becarefull on the fender to , those can be real nut busters !

muhahahahahahahahahahahaha

thanks for the info, Thats my next project after I get back from st. louis in a week. I got a pool, at a diff house , and a babe always around hell, its her car. And I found out about the nut busters putting my new cai on, ouch So basically, take the tb off, slide it out the way, and I can get to the stat easier??

With the combination of the tools listed above, you can accomplish this task without removal of the throttle body.
While you're at it, add a new radiator cap, too.
DOUBLE CHECK YOUR CONNECTION ON THE LOWER RAD HOSE ON THE RADIATOR!!
Losing mine/it fell off, cost me my 2.8 engine.
Oh well I got a 3.4 under my hood to make that problem go away!

MAKE SURE your lower hose has the coiled wire in it, so the hose doesn't collaspe under pressure.

Top rad hose, this detail does not matter, at all.
THIS IS NOT A HARD JOB, just lots of patience, tools for better grip and brews and babes for the job well done!
Hawaiian Sunset doesn't hurt either!
Aloha!
I keep thinking of the final Hawaii Five-O episode scene of the series.
Steve McGarrett overlooking Hawaii from top of construction building after the bad guy was "Book 'em Dan-O!"

Tracy Lord, the prono star stage name.
Came from Jack "Lord" of Hawaii fame.
Yes.
Know who the first name came from?