i am going to try this again the last time it kind of got off track. i have an 81 elcamino with a stock 7.5 rear end that got destroyed by my 350 and th 400. the car came with a 4.3 v-6 and a th 200. the 350 is bored out and stroked with longer rods + some other goodies i wont get into detail about. any way it exploded the drivers side spider gear and axel shaft .  i got a good deal on a ford 9" w/3.50 gears and a spool. question is i have never swapped a ford 9" into a chevy. does anyone know or have they done a conversion like this before. if so what kind of fabrication or modifications i will have to/ should make. it has ladder bars and  panhard rods to go along with it. If i have to i can fly solo with this i am a welder and can cut with a plasma, but i would like some kind of feed back just to point me in the right direction. the deal i got was too good to pass up. $300.00 for the whole set up. i would really appreciate any info or direction to info. thanks  

I'm still not sure what you mean by ladder bars and panhard rod and how or if this relates to interfacing with GM suspension mounts. Originally I assumed that this meant that the Ford had been modified from it's original leaf spring/Hotchkiss suspension mounting to those of the GM 4 point coil suspension. Apparently this is an incorrect assumption!

Setting up the Ford to interface with the GM suspension is a big deal. So if the set up you're talking about isn't compatible with the Chev rear suspension you will have to obtain or fabricate the inner and outer 4 point mounts, align and weld them to the center section and the axle tubes. The track width should be about right as most of these 9 inchers are about 59 inches and your Chevy should be about 60 inches. You will also need spring perches welded to the tubes.

The Ford input pinion is about an inch or so lower relative to the GM axle. This will require some adjustment to the upper control arms to roll the axle housing nose up a couple degrees to prevent binding the U-joints.

You should really talk with somebody like Currie, see tham at http://www.currieenterprises.com/html/custom/rearendproducts.htm  to discuss the issues and solutions. A freshly rebuilt and modified 9 inch from them is about 1700 dollars.

Frankly it seems that shopping for a 8.8 inch late model Ford or a GM 8.5" 10 bolt or the larger 12 bolt passenger car rear end would make life simpler and probably less expensive if the 9 inch you're looking at is not a bolt in.

Another possibility is that the ladder bars can be fastened to the GM chassis. This and the Panhard rod would require that you fabricate and weld mounts to the Chevy's frame. I've never come at a Ford rear into a Chevy coil spring chassis from this direction but I don't see any show stopping problems, especially if your a decent welder. Typical carpenter tools are adaquate to set up the dimensions and alignments, like a rafter square, tape measure, chalk line, level, etc. that leaves spring perches and shock mounts to obtain/fabricate and install. Then you could scrap the Chevy coil suspension and install the Ford leaf spings. This would require drilling the frame, welding some reinforcement around the holes to provide a bearing surface and installing mounts to accept the FoMoCo springs. Typically the front spring eye is solo mounted to the frame while the rear uses a shakle mount. All of these methods are do-able. The most difficult and expensive is to convert the Ford to the GM suspension but this is the simplest to install and keeps the chassis stock, the least expensive is probably modifying the Chevy frame to accept Ford leaf spring suspension. That of course assumes this 9 incher is based on a FoMoCo Hotchkiss rear rather than a coil rear. You can see that, I can't.

Bogie

thank you the info is greatly appreciated.  

Going way back to my original response to you, which then drug everybody into a discussion about 427 Tunnel Port Fords was not to talk about big inch FoMoCos, but to indicate that the 9 inch Ford is not bullet proof. It's ultimate strength is probably no better than an 8.8 GM 12 bolt.

The Achilles Heel of the 9 inch is in what Ford used to refer to in their advertising as the "Deep Hypoid" rear end. What they are referring to is the Ford design to get additional floorpan to driveshaft clearance by lowering the input pinion in relation to the ring gear. This puts a tremendous side load on the pinion gear and requires more substantial bearings to react those loads. This led FoMoCo designers to the straddle mount bearing where there's a couple main load carrying bearings on the input side of the pinion shaft as in GM, Dana, Spicer and other typical designs. But then Ford was obliged to add a pilot bearing behind the pinion gear to eliminate any overhung moment loads that result from the greater twisting  of the extremely low mounted pinion. So what looks like a better bearing design at first blush needs to be tempered with the realization the the lower the pinion mesh to the ring gear, the higher are the loads that want to pry this mesh apart. Ford tuned this "straddle mount" pinion into an advertising positive which seems to have lasted in automotive legend to this day. Also, because of these higher loads there is the problem higher heat generation and lost mechanical efficiency, some quips have pegged this as high as 3 to 4 percent less efficient than the equivalent size GM, Dana, Spicer , etc. This may answer why Fords running NASCAR back in the late 50's, when this rear end design came out, were the first kids on the block to also run an oil cooler on the rear end.

Happy Holidays---Bogie 

what i had found is some folks think this car has coils in the rear, it does not. it has lower control arms similar to ladder bars upper control arms running upward at an angle from the center housing to the frame, and shocks outboard on the axel.  

300  isn't a good deal if you need to put 40 hours in to it to use it

+ the parts you'll be changing to make it work...

a 73-77 a body rear is alot cheaper and is a 10 bolt...  and would almost bolt in...

a t-type regal rear is also cheaper..hell after buying all the other parts and redoing the driveshaft  a  grand nat. 8.5 10 bolt rear is cheaper..

or a malbu wagon 78-86 with tow package rear...

but u can get the 9" in there  latter bars are gonna su%k on the road..

moser can send ya the mounts to welt on that 9" to bolt it to the factory 4 link set up...  easier and will drive better...

and   P   S  your car is coil springs in the rear!!!!!!!!!!!!!

all el caminos are coils in the rear!!!!!!!!!!at least 64-87 

unless someone put leafs under there( I highly doubt it) it's coil...

the fact that you don't know what kind of springs are under your car..

scares me that your gonna weld in a rearend and put it on the road...

i can understand how you feel. but understand this i was not looking at the springs when i blew the rear, i am not a rear end person i have never messeed with rear ends before, ever, so this is undiscovered counrty for me. honestly with a lot of time i could fabricate and weld landing gear for a 747 under it, i just wanted to ask a question form some one who could point me in the right direction, i would like to plan things out. i sold the rear end to a friend with a mudder truck for more than i paid for it, actually  quite a bit more but that is ok. your feed back is greatly appreciated, thank you merry christmas and happy new year  

This explains why gm diffs were known to offer slightly less rolling resistance and thus a small gain in mileage