1973-1975 Cj5 Interchangeability

Hello all, I’m new to working on jeeps and looking for some advice.

My fiancé has a ‘73 cj5 that is very important to her, but needs a lot of work/parts. The important stuff is all there. Tub, fenders, glass, etc.
It has a cracked frame and needs a steering column. It ran when it was parked and the engine still turns, though I have not cranked it yet.
I’ve come across a ‘75 cj5 that appears to be an abandoned project that has all of the parts I need, plus extra.
I’m curious how well the parts will swap between the ‘73 and ‘75.
Any advice would be much appreciated.

 

Introductions | ECJ5 (earlycj5.com)

In factory form, these are both intermediates ('72-'75) and share much with interchangeable parts.
Look closely at the frame for cracks around the spring hangars.
Remember that most old Jeeps have had modifications which may affect the interchangeability.

 

What he said above.

My '74 is a mutt with a '76+ tub and a mix of parts from who knows what and it works well. You'll be in good shape with two intermediates as a starting point.

 

75 has a welded in floor. Transmission crossmember is 75 only. Wire harness was a disaster being half 74 and half what would become a 76. Overall frame and drivetrain are basically interchangeable as long as it is for sure a 75. Virtually nothing readily interchanges to a 76 and later. The spring bushings on 72-75 wore out on the way home from the dealer so those always need to be changed.

 

x2, on all the above, again be sure it is a 75. you can tell by the ID number. It should begin with
"J5" as the first two numbers. your 73 would begin with ''J3".

 

I believe Ol Fogie meant to say J3 or J5.

 

Supposedly, the 75 frames were made with better steel.

 

Supposedly, the 75 frames were made with better steel.

I never heard that one before.
Where does that claim come from ?

 

I don't remember. That is why I said "supposedly." I was hoping that someone else would remember?

 

I heard that of the intermediate frames, the '75 was the one to have. Not sure if it was better steel or better design as this was just before the introduction of the new model.
The steering box bracing and the transmission x-member tying in to the upper and lower portions of the 'C' channel frame may be source. This was over 40 years ago and pre-internet.
Maybe it was just a tale.

 

Comparing intermediate frames to the later AMC frame there is a huge change that is not not so good concerning the latter “box it in to rust it out” design.
Personally I’d choose the 75 frame over the 76 frame any ole day.
I have no direct knowledge what type of steel was used in the Jeep frames but imagine it was likely stamped from cold rolled 1045 carbon steel ???

Back in the day I believe model T Ford frames and the complete Bantam trailers used vanadium steel.
But I can’t document any of that.

I got a question for you Daryl……
What exactly is the main problem or difference you note about the 1975 wire harness ?
Couldn’t a guy with a 1975 CJ just revert back to a more basic 1974 wire harness ?

 

Yes they can be easily swapped out for a painless kit or similar. The bulkhead plug on the firewall was the weakest link. These also suffered from the later type headlight switch meltdowns as the wire size was simply too small for the load. Anymore it seams like every Jeep that I touch gets completely rewired and all new brake components on it.

 

Yes, Thank,you. Have no idea what I must of been thinking.. Post edited.

 

[QUOTE="What exactly is the main problem or difference you note about the 1975 wire harness ?
Couldn’t a guy with a 1975 CJ just revert back to a more basic 1974 wire harness ?[/QUOTE]

The 75 was a hybrid between 72-74 and 76+. It featured a bulkhead that the under hood harnesses could plug in to and not just a hole with wires like the 74 and older.
I Used the Painless 10150 harness for a 76+. Wiring under the hood and taillights was easy, under the dash was a challenge but it works great. The nice part was the lamp sockets and terminals were already installed for most of it. I had to buy and add the later CJ flat connectors for my tail lights and reverse lights so they would plug into the harness. I have notes on wiring the Spartan turn signal to the Painless 10150 harness should anyone need them. It was set up for the newer steering column.
Another thing to look at is the heat shrink butt splices that have the solder built in as well as the heat shrink terminals. You can get them on Amazon.

 

it looks messy but it isn't bad at all compared to what I removed. The original wiring had wiring fused together, wire nuts and spliced that was wires twisted together with one half-assed wrap of duct tape that was unwrapping.