FYI OP, if your truck is a 2017+ F350 it probably came with 5600# front coil springs (unless you have snowplow package then its 6000# springs) and then obviously you have the rear F350 leaf springs. Dropping to 4800# front coils like I did will lower it about 1.5-2" in the front and removing the rear block will lower the rear 3" exactly. You will have to cut the front bump stops on this setup and on stock wheel and tires (I have a platinum so mine is factory 20's on a 34" tall tire) you will "just barely" clear 7'-0" garage openings.
If you need to clear 81" you may need to consider going to 4400# front coils and pulling some leafs out of the rear leaf pack. This will gain you another solid 1-2" drop out of the front and rear
For reference...look at mine lowered (black truck) compared to Drew's stock height silver truck