I have a 1987 firebird forumula 350 and i wanted to have the transmission changed. I have another 700r4 i wanted put in. What would it cost me to get those swapped out? Also what all do the garages change? Like filters, fluids etc... and is that included in the estimate? I also am suppling the torque converter.

 

Shops have a book that tells them exactly how long is typical. It is called Book Time.
If the good book says (for example) it is a job that takes 5.5 hours, they multiple the shops hourly labor rate by 5.5. Some shops add time to cover small expenses like brake cleaner, carb cleaner locktite etc.
Then, they add the price expected to charge for parts, fluid etc.
Sales tax, and possibly some fluid disposal fees, and the quote is complete.
If the car is heavily modified, and strays to far from "stock" some refuse the job altogether, or add additional charges to cover the expected additional work.

 

In my area, that swap would run about $450