If it was that pot bound, hopefully you roughed up, loosened up the rootball before installing it in the ground at a depth no deeper than it was growing in the pot - or slightly higher. Those are the two major concerns with planting containerized rhododendrons, that the roots are freed from their pot shape so that they can extend into and establish in the surrounding soil, and not positioned so deeply that those surface roots (typical for all rhododendron) are unable to function.

Be sure to give it supplemental water as needed for the next several months. Nice find for the price ;)

thank you.
we did plant high.
and i did use the shovel to ruff up the root ball.
things be looking good.
we be getting some nice rain today.

Pull it up and dig out the amended planting hole back-fill, replace with same soil that is around planting hole - without adding other material.

Mulch with wood chips or similar material. Water in well, and keep watered whenever there has been less than 1 inch of rain per week.

Stake for one year if blowing over in high winds seems possible.

Mauling the outside of root-balls serves merely to damage some of the newer, outer roots that you otherwise hope will be extending into the new planting site as soon as possible (the amount of this that occurs varies seasonally). Root deformities that matter are inside the ball, where you may need to go to pull open or cut roots that are so crazy they may cause the shrub to fail many years down the road. The presence of these kinked, j-shaped, bound, circling or knotted main roots is frequent, due to apparently pandemic careless practices at commercial production facilities.

Since the roots of heath family plants such as rhododendrons are often dense sods that just come apart in chunks when you try to get into them, I usually just leave them as is when planting. If a specimen of this affiliation has obvious problems visible from the outside I don't buy it in the first place - there are a lot of other kinds of trees and shrubs I can grow here.

You should know that some of the planting advice offered above by bboy - non-amended soil, unmatting of the root area - is directly contradictory to what experienced rhododendron growers worldwide would advise.Rhodyman's website has excellent information about how to plant.

Too bad you took the pot off the rootball before you exposed it to drying winds on the trip home. I hope you didn't travel with the plant upright in the truck rather than laying it down to keep it out of the wind.
Since it was in a pot, the rootball is probably small in relation to the rest of the rhody. Because of that, watering on a regular basis is paramount. The plant needs to maintain capillary action between it and the surrounding soil. The amount and type of amendments you choose shouldn't interfere with this. With that in mind, I don't usually rough up the rootball. Rhodie roots are very fibrous and will grow out from the previously confined condition just fine as long as capillary action is maintained and the soil has sufficient organic matter for a good root environment. If there is a big difference between the rootball and the ground, the rootball can shrink and separate itself from the soil, causing it to dry out very fast.
I don't see where the inside roots of a rhododendron will interfere with it's growth. Some other trees and shrubs yes, but not rhododendrons.
Mike

Here is a link that might be useful: My Photobucket pictures.

Thank you for all the comments.
The truck ride was maybe 3 miles. 25 mph. No worries there.
The root ball was 20 inches across at the top and about 12 inches in depth.
I'll post some pix of the blooms later in the year when the buds open.
I believe this is a red rhody in terms of flower color. Some old flowers remain on the plant. Though dried and shrunken, they appear to be reddish.