I have a 78 Aspen wagon with a 318 and I am swapping it out for a fresh 360. I remember that the 318 and the 340/360 had a different mount on one side.
I went on RockAuto's site and they are showing the same part numbers for both 318 and 360. What gives? Any input on this is greatly appreciated.

The cushion is most likely the same. The cushion to block brackets could be slightly different. Most likely easy to make fit. Oil pans as well as converter or flywheel are different as well.

The bracket on drivers side is different or you may be able to shim the one you have.

The driver side upper stamp steel block mount is wider or narrower, CRS, than the 318 are. I have seen guys using washers on the bolts as shims, but I would rather buy the correct mount and not have to worry about the nuts coming loose or the shims wearing and getting loose
The 360 is externally balanced and should have an external balanced balancer on it and the torque converter have weights welded onto them for external balancing also

The left side bracket that bolts to the block on a 318 is wider then the same side bracket on a 340/360. You can use the 318 bracket, the front side of the bracket bolts directly to the ears on the block, and the rear ear of the bracket is about a 1/2" away from the ear on the block. A nut for a 1/2" bolt is a near perfect spacer. It fits nicely between the bracket ear and the block ear, and the mounting bolt passes through nicely. Tighten the bolt just like you do the other two, and life will be grand. I've never had a problem with the bolts coming loose. The replacement rubber part of the mount is the same for both of the brackets on the motors.

The torque converter (or flywheel if manual trans) has to be balanced for the 360, or you will get a bad vibration.

F bodies use spool mounts, not biscuit mounts. As Poorboy said, the 318 mount will fit on the 360 with a spacer. Poorboy's advice on the balance issue is also correct.

All the 318 accessories should bolts right up. Exhaust manifolds should, but test fit them on the engine stand first.

You can see the space in the following picture from my 318 to 360 swap in my diplomat.

Another in a long list of brite ideas from ma mopar.

I drill and tap them, put 1/4-20 Allen heads in there with loctite

Yes to Sniper's responses. I've done a few 318 to 360 in Diplomats and spacers worked just fine as he writes One time I bought new poly mounts and that was probably a mistake due to the vibration transfer.

Yours auto or manual trans? As they mentioned make sure you have the converter properly weighted or scalloped flex plate.

I've done several 360 swaps on late 60's and early 70's a-bodies. I had never done the swap on an f-body before. Will be running a 727 and already have the proper B+M flex plate. Will be using headers for the exhaust. I know the driveshaft will have to be shortened.
Was just curious as to why RockAuto was showing the same numbers for complete mount assemblies on both engines. Guess I will shim the new mount. Thanks guys.

Because you can shim the 318 mount to fit the 340/360. But you cannot go the other way. So the aftermarket cheaped out by just making the 318 mount. Of course, the question in my mind is why Chrysler make the mount ears different?

Who knows why most automotive engineers did half the stuff they did over the years? Maybe the bean counters figured they could save two cents per 340/360 block by moving the one ear on the block, or maybe some guy in the design department wrote down the wrong measurement for the casting department on the 340/360 blocks, or maybe the guy in the casting department read the numbers wrong on a Tuesday morning after a long hard weekend.

And my Mopar 340 race block uses 318 mount. So had to get one as the 340 one won't work.

The 360 was a factory option, someone surely has the bracket, if originality is a factor. Me, I would space it.

Is the Rock auto part just the insert? That would make sense.

Sniper posted a pic of drilling out the air injection port. The first set of headers i installed on a set of these heads made me ponder, until I realized they were completely blocked with carbon, so I just ignored them, and as long after that I knew of the where abouts of that car, it never was a problem. (next owner liked the car so much he kept it until rust killed it).

They didn’t want the wrong parts put on a car is my guess

Yes you'll have to shorten driveshaft. I've had several shortened on my M bodies. No local shops to balance them after shortening. The shop that shortened them insisted I did not have to have it balanced after shortening. I was skeptical but so far so good and I have not had a problem but I sure would prefer to have it re-balanced. I believe you'll need a different yoke as well. yoke on the 904 transmissions is smaller than the 727

The story I heard is that an engineer caught a mechanic with his wife, and as a society they have sworn revenge.

Randy

If magnumswap.com is still around they had some pretty good info on swapping those engines.

Some 360s came with the 998 and 999 version of the 904. Worked fine. And we ran a warmed up 999 behind a warmed up 360 in a Scamp for several years with no problems at all. There are several advantages to running a 904. Quicker ETs is just one.

I have had several drive shafts shortened without rebalancing. As long as the ends are clocked the same and the shaft is welded back up on the lathe while turning they have been fine with no ill effects. Bubba's booger welds would not work well though.

All of the new type bolt through motor mounts on cars from about 73 on to late eighties have the oval bolt through mount isolators. This is what the parts stores sell as a motor mount. No brackets included. .

advance auto parts shows the complete mounts with the steel bracket . part numbers 2325 and 2326. can be bought for under 25.00 plus tax. they are the same part number for 318 and 360.

after i looked at mounts at aap online, i got an email for 15% off. i called the store and was told that you get 25 % off if you come in, order parts and sign up for speed perks. i will go in tomorrow and order the mounts to put on shelf. here are pics of parts. sorry pics are sideways.

I've shortened lots and lots of driveshafts without a lathe, and without rebalancing them. They have been in dirt track cars, 10 second drag cars, heavy duty work trucks and street cars. Correctly clocking the yokes and making sure they are straight in the shaft tube solves the balance issues, as long as the shaft wasn't bent to start with and the shaft doesn't have a rubber mounted core inside that is in the way of the new yoke position. The yoke also has to be the correct size for the tube used, sometimes shortening the shaft will encounter a change the diameter from where the yoke originally fit and where it ends up on the shortened tube. I won't shorten those shafts.

If you want the correct mount you can find NOS ones on ebay at times. Or as said just use the one Rock auto sells and use a shim/spacer/ washers.

I will just use spacers on the mounts. As for driveshaft shortening, we have a very good shop in town that can shorten and balance it. I have used them before and been very pleased with their work. I am totally aware of the air injector holes under the exhaust ports. Discovered how to deal with them 35 years ago, when I had a nasty leak after swapping manifolds for headers.

Aftermarket got cheap and doesn't want to do two different mounts. When I had to replace my mount years ago they were still selling them with two different part numbers but it was the same 318 part in all the boxes.

Figures. Reminds me of heater cores that don't fit in M bodies despite the aftermarket saying they do.