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.