Just picked up this redhead

Jim: I just know there are a couple different kinds of valves and they may not both be compatible with the different gasses. I don't know the specifics. That question has been asked/answered a few times on this forum and I know our illustrious leader is working on a HOW TO thread on converting from one gas to the other. But it can be a complicated process and it isn't ready for release yet.
Larry might be able to answer some specific questions, but I cannot on that front.
I also cannot tell you if those orifices from anderson & forrester will work. I rehab weber grills and have a supply of spare parts to include entire LP and NG manifolds. So, when I convert, I just swap the entire manifold and don't worry about all the other intricacies involved. If you can find a compatible donor grill to grab an LP manifold from, that is by far your easiest solution. If you want, I could sell you one, but shipping is rough. PM me if you are interested.
The valves themselves on the older deep box Genesis grills are not compatible (safely) between gases. I.E. if you have a NG manifold putting LP orifices will not make it work properly with LP and vice' verse'. The real danger is if you try to swap to NG size orifices on an LP manifold. The internal valving will cause the grill to "flame out" on low and sometimes medium. However gas will still be flowing into the burner(s). And may have slight flame in spots. Meanwhile raw unburned gases are collecting inside the fire box. Eventually they will collect enough and boom. Or you lift the lid, it gets a sudden gasp of oxygen down there and a little part of flame will ignite it and cause a huge fireball. Bye bye arm hair, eyebrows, etc.
It is impossible to tell what a valve really is by looking at it. Externally they all look the same
I know my cook box is filthy. It is my next project. My problem is I need to drill out the evil bolt on the left side. I have a question about the bolts or studs that hold the manifold on. The bolts are too short to get a nut on. Is this a somewhat normal problem, and should I just drill them out or are the a part of the cook box. If I should drill them out does anyone know what size bolt I replace them with?
I am hoping Bruce will weigh in. Looking at your pictures I would probably carefully use a cut-off tool and then drill out the remaining plug that is left behind.
Yah, what Larry says. I always try "punching" them out, but there is a chance you could crack the aluminum cook box. So, drilling them out is the safe way to go.
Those are 1/4" bolts on the left side and the right side. I think 2" long on the left and 1.5" long on the right.
It’s going to be very nice. And after all in the end it is a grill to GRILL on and enjoy! A redhead that will live on for many years of enjoyment rather than being consigned to the scrap yard.
She looks much better than when I bought her. Just a couple fiddly things left to do, but she works a treat. I did it on the low budget, and kept as much as I could from the original. Thank you everyone for encouragement, information and help with parts Bruce.
I think the inside of the Firebox still needs more cleaning, both on the inside wall and lid.

For you it probably does. I am making a grill to use. It will get dirty soon enough. In fact probably tonight.
Nah, all that thing needs now is a 1.5" Ribeye to complete it.

Jim: Did you fire it up. Did the manifold work out OK for you?
Yes I did, and yes it does. Thank you once again. Just burning it in, and I'm gonna throw some meat on it.
It will just be burgers tonight. We get them from a local coop. They have about 8 farms that make local grass fed beef, pork and lamb. Super yummy quality meat.