As I promised on the earlier Back Seat thread, here is a sketch of an easy-to-build, light weight, very serviceable Jeep back seat. �I have tried to contact the owner of a 1963 CJ-5A that still has a rear seat I made for it more than 40 years ago in order to get measurements and pics. �I have been unable to do so. �I still remember the dimensions so I have made the sketches below (but a picture is worth a thousand words-still try to add later).
I made several of these in my younger days. �The first was for myself. �I did not come up with the design. �I saw one when I was visiting a friend out of town. �I'm not sure he was the designer either. �You can alter the design to suit your particular needs. Please ask questions for clarification.

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You can see that the plan shows a different hand rail on either side of the seat. �The one on the left is a good handrail or somewhat of a safety rail for children. �The one on the right allows for easier access over the side (and simpler to make). �I have drawn in phantom lines showing the backrest of the seat. �It is made of plywood. �It must be notched on each end to accept the radius of the frame. �It is screwed or bolted to the frame three places across the horizontal member and one place on each vertical member. �The bottom cushion is made from plywood cut to fit the bottom frame. �I used 1 1/2 inch foam rubber on the back rest and 3 inch foam on the bottom. �High density foam is best (and more expensive). For cosmetics I rounded the top corners of the backrest and front corners of the bottom with a 2-inch radius. �I covered the foam with Naugahyde (vinyl) and stapled it to the back or bottom of the plywood. �I had an upholstery sewing machine, but most modern housewife sewing machines do a fairly good job on most vinyls. �Use the heaviest thread possible and a large stitch. �
Here is another sketch itemized with materials callout.
#1 Seat End, make 2 each from 16 or 17 gauge mild sheet steel. Bend 90 deg to dimensions shown
� � (Item will bend to a sharper angle and fit better if heated. Most steel suppliers will cut and bend to order.)
#2 Long Seat Bottom Frame, make 2 each from 1/8 in X 1 in 1 in steel angle.
� � (Length to fit inside your Jeep bed 3' +0/-?*. �Front seat bottom frame is located 2 inches higher on Seat Ends
� � than the Rear seat bottom frame in order to give pitch to the seat.)
#3 Short Back Support, make 2 each from 1/2 inch electrical conduit (EMT).
� � (Bend conduit with a standard conduit bender--rent or borrow.
� � Flatten the forward end of conduit for easier welding to seat bottom frame.
� � Determine length of lower leg by centering bend on rear long seat bottom frame.)
#4 Short Seat Bottom Frame, make 2 each from 1/8 in X 1 in X 1 in steel angle.
#5 Long Back Support, make 1 each from 1/2 inch electrical conduit (EMT)
#6 Seat Back, make 1 each from 5/8 inch plywood. �Make seat bottom from plywood to fit seat bottom frame.
NOTE: Take necessary precautions to not inhale toxic fumes generated when welding electrical conduit.
*Seat can be made to fit snugly inside of fender wells. �However, you may want to leave enough space to add padding to protect the painted fender wells. �Some have used padding, such as carpet, to make a snug enough fit to keep the seat in place without fasteners. �Others have simply drilled a couple holes on each end of the seat and bolted it to the fender wells.