New to forum with 'A' automatic transmission q's.

A few years ago I 'sorta' looked into whether I could put a 518 transmission (3 speed w/o-d) into my A 108, but then got busy with other stuff. I looked at some old notes I scratched out about it but don't know how accurate they are. At the time I was told the following but don't know if either are true –

1 – A post 1988 518 would bolt up to my '67 318 but I might have to rig up some custom linkage. Was also told that the 518's rear mount was on the bottom and I might have to fab some type of cradle.

2 – The 518's overdrive unit is housed in the tail cone and all I'd really have to do would be to swap out my 727's tail cone for the 518's.

I'd first like to know if any of those statements are true, and secondly, has anyone here swapped out their 727 for a 518 (3 sp w/o-d).

TIA.

I've been thinking of doing the same thing but my 108 is a 3 speed manual , with gas at roughly $9.60 a gallon here i need all the mileage i can get out of my dodge , I've got a friend looking out for a 518 box for me , a few people i know reckon it will bolt up to the older 318 and the mount is on the bottom of the tail housing , I don't know whether the o/d unit will slip onto the 727 , would be cool if it did, there's only one way to find out ha ha ,
Good luck and let us know how you get on
Wayne

Thanks for the response, Dragsterbus.

I googled '727 to 518 swap' and came up with several how-to links but it's more complicated than I thought.

Some years ago I considered the mileage factor too and replaced the original 355 rear with a 276. If I've calculated correctly, with a 518 I'd get close to the same mpg with a 3.90 or 4.10 rear as I do now with the 276 and it'd have a tad more pep off the line But it'd be a little more trouble than I'd want to get into right now.

The 276 isn't that slow off the line and what's nice about it is being able to punch it at 60 and have it kick down into second gear up to 75 mph. Thought it'd be nice to do something similar with a 390 rear or lower.

Sorry folks - didn't realize this topic had already been discussed here, sorta. This came up on a google search -

https://vintage-vans.forumotion.com/t23460-pact-727-to-518-conversion-kit

Guess I didn't use the correct wording when I searched the forum archives.

Anyway, I'm wondering if mattimus made it conversion ?

rebar wrote:
1 – A post 1988 518 would bolt up to my '67 318 but I might have to rig up some custom linkage. Was also told that the 518's rear mount was on the bottom and I might have to fab some type of cradle.

Shift linkage will be pretty much the same, may require some fiddling to get the shifter and the trans to both be in the same locations at the same time.
Throttle pressure, often called kickdown should work, but if you change things up, may need some fiddling too. Cooling lines should work.
All auto transmission mounting flanges are on the bottom except our vans and some motorhomes, so this is something that will need to be addressed. Since the tailhousing is different on the 518, you can't use the van tail, it would remove the OD. You can adapt a B van hanger to an A van, allowing any bottom mount 727. A 518 may require hanger modification, due to the extra width. The driveshaft will have to be shortened. You can search online for lengths of the different transmissions, but I'd suggest waiting until the trans is mounted and take direct measurements for the driveshaft.

rebar wrote:
2 – The 518's overdrive unit is housed in the tail cone and all I'd really have to do would be to swap out my 727's tail cone for the 518's.

Yep, just swap the tailshaft. Oh, and the rear output shaft (requires complete disassembly of the trans). Oh, and the hydraulics that provide the O/D planetary it's engagement. Sorry, it's not a simple bolt-on!

Here's a picture.
518 on the left, 727 on the right.

RodStRace wrote:
Sorry, it's not a simple bolt-on!

Thank you Mr R for the detailed response and for posting the picture. I tried to post links and pics a couple days ago but I was still within my 7 day newbie period. In one of the forums I ran across the guy ended up saying it'd be easier and cheaper to just go with a gear vendor. After seeing how much trouble it'd be adapting a 518 I'd tend to agree with him, although the gear vendor's high gear isn't as high as the 518's od. Think I'll just stick with what I've got, and dream.

A gear vendor is longer. They are not cheap.
They require a bottom mount and hanger too.
They are stronger, but how much power and weight are you planning on?

RodStRace wrote:They are not cheap.

Yeah, 2k+, and I really don't want or need to split 1st and 2nd gears. And, as your pic shows, who wants all that extra gearbox extension? I was just wanting a tall overdrive - that way I could justify buying a 456 rear. Looks like I won't be getting either anytime soon.

Here is an article on swapping in a 518 with lockup.
http://www.transmissioncenter.net/SwapInformation.htm

In the article, all the extra stuff is to make the OD and lockup 'automatic'.
I've got a project that has a 518 without lockup. It requires a single button with two wires for the OD.
Much easier, but you do lose the lockup and the extra MPG.
As noted in the article, Dodge changed the naming structure of all the transmissions around this time (early 90s). It's also called the 46RE (4= 4 speed, 6= strength, R= rear wheel drive, E= electronic controlled).
Mine is a 46RH, with the H= hydraulic controlled.

More info
http://www.hemmings.com/mus/stories/2006/07/01/hmn_feature15.html

Thank you sir. I previously came across that first article and it just made it seem a bit much to deal with currently. The Hemmings article makes some useful points. The following article mentions minimal costs/labor which sorta has me throwing up my hands to leave the idea for more enthusiastic folks.

http://www.hotrod.com/howto/43323_mopar_overdrive_transmission_swap/

Yep, as that article points out, it will bolt up, the linkages and lines work, and the mount is the big change.
Remember that the floor mods will not be needed and the adapter to go from small block to big block is also not needed if you are staying small block.
Find a good or rebuildable 518 in an 88-92 pickup or van with the 2-pin OD connector.
Measure the distance from the back pan rail to the floor on your current trans, remove it and bolt up the 518. Block up the new trans into the same position and fabricate a mount. Get the drive shaft shortened or a new one, and you are pretty much there.

Your location just says NW, so I looked in the Portland Oregon area.
The right year engine and trans for 600 bucks. A 360 Magnum is a better engine than an early 360, you just have to swap intakes to bolt on a carb, and swap in an older dist.
http://portland.craigslist.org/wsc/ptd/3340629849.html

This wrecker doesn't list the trans, but may have the right one cheap.
http://portland.craigslist.org/clc/ptd/3360832875.html

It wouldn't be too much of a project if I wasn't short on shop space and time, both of which are occupied by my little business. Maybe I'll have a little more space and time when the economy tanks again...