I disagree with much of the comments in this thread.

I daily drove my satellite for 10 years with a thermoquad on a 440. Anyone who says you need to rekit them every year, constantly retune them, deal with leaking phenolic bowls, live with poor throttle response and suffer with an overall finicky carb is either full of bull or just regurgitating what they've read on the internet.

A well tuned thermoquad is the next best thing to fuel injection. Number 1 issue is guys don't know how to tune them, then blame the carb for their own shortcomings. There is a lot of tuning that can be done on them without changing parts. You bend linkages to tune them. Number 1 issue is getting the choke setup right. You tune the choke so the choke flapper door does not fully close. It should stay open in the front by a pencil width. If yours closes fully, you've set it up wrong. After that, even at below freezing temperatures, mine would fire up easy, and I could kick it down and drive away after 30 seconds without any hickups. Then you will need to get your idle speed/mix setup right, however that's as easy as on any other carb. The hard parts come with getting the secondaries setup, many guys don't understand the relationships between the secondary air door tensioner, travel limiter and accelerator pump adjustments. Just because it looks like it's setup right, doesn't mean it is.

After I got mine dialed in, I drove it for many years without touching it. I only had to touch it again when I upgraded cam and cylinder heads. Throttle response is crisp, better than any newer pickup truck I've driven.

I've never seen a thermoquad with a leaking phenolic bowl. I did have one that was cracked, because the carb was thrown around in a pile of parts after it was removed from the vehicle. Not really the fault of the carb.

Biggest favor you can do yourself is to study the vaanth thermoquad guide (google it) and only run the 6000 series thermoquads. The later thermoquads, the 9000 series are emissions carbs, have varying levels of additional ports and are not preferable. The ones with a part number starting with a 6 are good pre-emissions carbs. Mine doesn't even have provisions for the charcoal canister, just one vacuum port for the distributor.