The light bulb tubes are 1 inch by 48 inch T8 connectors. We've been switching to LED tubes and have been happy with them so far. Get the 5000K color temperature ones so they match. If you get 4100, they will look a little pink and yucky.
We've been buying them at Lowes. Item # 778117 Model # 75076 The UPC is 0 46135 75076 2, Amazon doesn't have them yet.
They are a pretty new product and go in and out of stock and on and off sale. They are confusingly similar in packaging, so make sure you get the right ones.
Also, hardware stores are getting to be crap about stocking shelves correctly, so order them for pickup or delivery - don't waste your time trying to find the right ones.
Lowes also recycles the old mercury ones for free.
The cost on the LEDs is a little higher, and time will tell how long they last... but given that we've not been good at replacing tubes in the past, any extra life is nice to have in addition to the power savings.
The particular tubes we're using have only a few reviews, and they're all for DOAs... though ours have all worked great. People are more apt to complain, it seems.
The light fixtures are 12 feet up, so you will need a bit of ladder. The extension ladder is the only one that Freeside owns that is tall enough. Randall has a Gorilla ladder that will reach in the A-frame mode.
The LED tubes in use are 12 watts each, 1600 lumens, 82 CRI.