Dont know the OEM part number. But Carid sells alot of sharkfin style replacements. Youll just want to be careful to reseal everything, to avoid leaks.
https://www.carid.com/toyota-4runner-antennas/
http://www.toyota-4runner.org/5th-gen-t4rs/231576-dobinsons-5th-gen-toyota-4runner-suspension-options-lots-choices.html
Here is the Dobinson thread. Tons of options and they all are well explained on the front page.
Check out Dobinsons struts and coils. Spacers are the easy "fix", but they will subjectively make your ride a bit more harsh. You can get a 1-1.5" lift up front with the C59-296 or C59-300 front springs, and C59-599 or C59-505 rear springs (if you want to keep some rake). Replace your struts...
But then again, I dont know your situation, and how soon you need a vehicle. If I was you, I'd just have the dealerships make offers, and have them come down in price against each other. Maybe easier said than done.
Dealing with them now, but down in the Springs. They have hit TrueCar pricing for me. Fairly easy to deal with, as long as you don't have to have something immediately.
GF took delivery of these, while I'm gone. Got so many confused questions asking what they were. They look great though! Can't wait to get them installed. When can we expect rears" ;) I have a 2.5" Dobinson spring that needs some bump stops.