Six7390gt

I'm trying to get back up to speed on Holley carbs after taking about 40 years off. Are there different thermostatic springs for the hot air choke? Looking at Holley's exploded view - linked below - it looks like #19 - the thermostat housing assembly - is sold as unit. If the springs are available separately, how can I find the part numbers for the different springs?
https://documents.holley.com/techlib...loded_view.pdf