I'm looking for an F36T12/HO 2 or 1 lamp ballast. I found some lamps and I want to convert some fixtures to them. It needs to be 120v. I'm hoping someone knows the model numbers of the ballasts?

Here are two Advance YS-2S85-TPs. Each one can power 1 or 2 tubes. Kind of expensive but it is a pack of two ballasts.
https://www.ebay.com/itm/255543314322

 The listing says 120 volts, but the ballast label is red and says 240 volts.

@Ugly1
That is true, I guess I don't know how to read lol

Yes, I had come across that one and didn't buy it for that reason.

Advance RC-2S85-TP is the 120v version of the ballast posted above.

For shorter lamps and for converting existing fixtures the Universal 631-LH-TC-P is probably a better option. The OCV is lower so shorter lamps aren't as likely to instant start and the shorter ballast height means it will fit into more fixtures compared to the Advance.

 If u  have two  15  to  20 watt  preheat  chokes  and  combine the  two  in  perallel.  It will run a  F30T12
High output quite easly just unsing  two  preheat chokes
 And FS 2 starter.   

@funkybulb
That is a very good idea, common 18-20W chokes provide 240 ohms at 118V, while (according to my calculations) the tube needs ~125 ohms. Two 18-20W chokes in series gives 120 ohms which is close enough. Plus preheat is a lot cooler than RS in my opinion.

@funkybulb
That is a very good idea, common 18-20W chokes provide 240 ohms at 118V, while (according to my calculations) the tube needs ~125 ohms. Two 18-20W chokes in series gives 120 ohms which is close enough. Plus preheat is a lot cooler than RS in my opinion.

a 20W *Reference ballast* is 240 ohms, but many production ballasts are not, especially not your common 14W-20W choke some of which dont even drive a F15T8 at full power, just keep that in mind when trying to work things out like this

@LightBulbFun
Excellent point, I did not consider that. Of course an RMS ammeter has the final say, but if you can find chokes that are just for 18-20W tubes it would probably be better than those 14-20w ones.