Sure.
Unbolt the master cylinder assemply from the booster, pull it away from the booster and leave it hanging by the steel lines.
Disconnect the vacuum line that runs from the intake to the booster. It's a pre-bent steel line coupled to a 1/2 rubber vacuum hose near the booster. In my case I couldn't get the hose off the steel line so I slit the hose along its length and pryed it off the steel line.
The booster has 4 studs in a square pattern that extend thru the firewall and are held on by 13mm (if memory serves) nuts inside the cab up and behind the brake pedal. 3 out of 4 nuts were pretty easy to get to, just pull back your carpet/vinyl a bit to expose them. The 4th required a u-joint socket adaptor and took awhile to get out. The booster "push rod" slips over a stud on the brake pedal assemply and a retaining clip holds it in place. A pair of pliers or screwdriver will remove the retaining clip, slip the booster push rod off the stud, remove the nuts from the mounting and the booster is free.
Note: there is a short steel machined cylinder stuck in the master cylinder side of the booster. Your new booster will come with it's own. Make sure it stays inside the booster or your brakes won't work!
I can't vouch for the 9" dual diaphram booster, but both the 10.75" single diaphram and the 10.5" dual diaphram booster have the same bolt pattern and push rod so the new booster will bolt right into place, connect up to the brake pedal assembly. Was a little nervous moving the master cylinder around to allow enough room the put the larger booster into place but I got away with it
Oreilly's didn't have 1/2 vacuum hose so I used 1/2 fuel injection hose which has worked fine so far for the replacment booster vacuum line. That with a hose clamp and I was back in business.
As far as how to identify here are some pics that make the visual difference pretty obvious, at least when it's off the truck. The booster have stamp id's on them, as I recall about 1/2" letters. The 10.75" single is stamped "AB" and both the dual diaphram boosters are stamped "HR". You could see the "AB" stamp on mine while in the truck. Just take a flashlight and take a close look at the master cylinder side of the booster body.
For the purposes of this mod I wouldn't bother with the 9" booster, cost is about the same as the 10.5". This is all about increasing the area of diaphram and thereby increasing the force applied thru the booster to the master cylinder and reducing the amount of pedal force needed to stop the truck.
From my research the standard brake system came with either no power booster or the 10.75" single diaphram booster. The heavy duty brake system variations came with the dual diaphram boosters at higher cost.
10.75" single diaphram:
10.5" dual diaphram:
9" dual diaphram:
Hope this helps!