'63 tub on a '74 frame

I'm sure this topic has been beat to death so I'll try to keep this short and to the point.
I found a '63 tub to put on my '74 frame. I've done some research and it sounds like an easy enough modification to make one fit the other.
My question is... what are your thoughts about the different gas tanks and locations?
Here's what I'm wavering on...
The '63 has it under the drivers seat. That location seems like it'd be more protected from offroad punctures and rock damage than the '74
Any opinion on that?
I like the look of the filler neck location on the '63 and... it's one less thing to change if I keep it there.
I don't know the fuel capacity of the '63 tank but if it's considerably less than the '74 I'll keep the '74. That 360 of mine doesn't get very good mileage.
Can someone tell me the capacity of a '63?

I know, I know, I know... '63 is dangerous because the tank is in the passenger compartment and it could leak and I could die. None of that concerns me.

So... safety aside, I'd like to hear your opinions on one location vs. the other.

I'd also be interested in hearing from any of you who have done this tub swap and if you've come across something unexpected.


Thanks

 

The firewall comes to mind as a big difference the heater box out of the 74 won't fit. steering column and brake master will also be problematic. No idea on the tank but twelve gallons seems to ring a bell.

 

Even less - 11 gallons IIRC. Small. The rear tank is 15 gallons.

If you have a '74 chassis complete, you can run both tanks.

The main problem with the under-seat tank is that it leaks and stinks. Any side hill will put liquid fuel against the gas cap and it will seep to some degree. And the cap is vented, so any fumes exit right there under your left elbow. This is not so different from other old cars, but modern cars do not smell like gas the way old cars did. The '74 came with a vapor recovery system, that eliminated any gas odor. Vapor recovery won't work with the under-seat tank.

The rear tank is not an issue on the trail. A CJ's break-over angle, even with the tank, is not much affected. There is a factory skid plate for these tanks that provides ample protection. If you don't have the skid plate from the '74 chassis, the '76-on skid plate will work, and it's available aftermarket.

So, I'd heartily recommend keeping the rear tank, and I would consider eliminating the under-seat tank, if it were mine. Or run the under-seat tank as an auxiliary - easy,and been done on lots of Jeeps.


Yeah, firewall is pretty different. Steering column is in a different location. Driver's seating location is different. I'd think you could make the '74 heater work, but you'll need to modify the firewall for the swinging pedals (close the big hole for the heater) and you need to use the '74 dash.

 

Under seat tank is 10 gallons...I'd keep both.

 

I've got a complete and running '74 now. The '74 tub is fiberglass and junk and that's why I'm looking for a replacement. I can handle adding & filling firewall holes. I hadn't thought much about the heater but I'll bet I can make that work too. It doesn't do much good anyway without doors or a top.
Tim, I think you've convinced me to run the rear tank. I'll remove the under-seat tank and maybe turn that floor recess into storage. Since you seat location... The previous owner notched the rear wheel well and moved the seats back a few inches. I'm assuming I can do that to the '63 tub as well. I don't have any of the original seat brackets and I don't care for the homemade ones that I've got now so I had planned on fabricating my own, possibly tying them into a roll cage.

 

yep
2 tanks much better than 1.

 

Driver's seating position changes more to the left in 1972. You sit more outboard in a '74 than in a '63. Passenger seating location is the same. Front to back seating position is the same. Column angle may be a little different.

 

Floor recess you say? Where the under-seat tank is? Sure this isn't M38A1? I think those have depression in floor to fit a larger tank.

 

I think you could make the old tub fit the frame . but your going to need 72 and later fenders and hood . different WB . 81" vs 84"

 

Right now I'm working on getting the bodywork done on my 1964 CJ6. Once done I'm going to fit up a late model front end and flip it upside down. Going to mount a 1982 CJ8 frame to the grill shell then start setting hat channels and body mounts to match. Figure it will be easier to do the modifications front the top side than laying underneath of it.

 

Yes, they do.

 

I lied about that part. I haven't yet looked at the '63 tub in person. There is no recess, the picture I was sent is deceiving. I guess the additional toolbox is out of the question.

 

You can have storage under the driver's seat, or a gas tank. There's no room for both. And a tool box like on the passenger side won't work, because the driver's seat does not fold and tumble.

Some have gone so far as to remove the toolbox and install a second fuel tank on the passenger side. Having extra fuel capacity is very useful.

 

Boyink put a water storage tank under the driver's seat instead of a fuel tank. You could also put a security drawer there that pulls open forward. That's what I intend to do on my '6 project...

 

I believe It was Duffer that did a nice security box in his 3B. My 3B came with tanks under both front seats and the tire carrier can hold two cans. Sometimes, I might put one can on the rack depending on where we are going, I think I needed the can once (I wasn't out of fuel but it was a good place to add gas and get some of the weight rearranged), and a few others have needed a bit of spare fuel at times.

 

MTS makes a tank to fit under the passenger seat for when the tool box is removed. A filler neck indent would need to be added along with attendant fuel lines, etc.

 

You can also address the fuel guages if you do the second tank. It was my brother that put in the second tank under the passenger side seat, he bought it new and he had a radiator shop switch the filler location for the right side tank. Filler indents were easy to find then. I decided to deal with fuel guages, I swapped the stock guage to the right side tank and ran it through the stock cluster. and bought another SW setup so I have two guages and just the simple fuel valve between the seats to change tanks.