Technical Difference in 3M 08509 and 08609 sealer

Does anyone know the difference between the 3m 08509 and 08609 sealer? I need to seal a heater box to a fire wall. Everything I am reading online makes these two seem interchangeable?

Thanks,
Brandon

 

bump up....inquiring minds want to know.......

 

It's in the composition and work time.

the 08509 has about a 40-50 minute work time and sets up kinda hard, whereas the 08609 has a 10-20 minute work time and sets up a bit more flexible.

I suppose it all comes down to preference for this application. Personally, I think I'd want something a bit more flexible for expansion, contraction, and to make it a bit easier to remove and replace or repair, should the need ever come up.

I have also used 3M strip caulk for stuff like this.

 

I find that a lot of products these days don't actually have a description of what they do, on the label. All the space is taken up with warnings and hazard language, sometimes on a separate label viciously glued over top of the useful info.