1967 318/727 advice needed

[Bulldozer]

i need a couple answers from you guys if you can help...i have a 73 duster 225/6 with a 3 speed manual. ive been searching high and low for a 318/360 to replace it with. i have a guy bringing me down a 318/727 out of a 1967 coronet that has just been rebuilt and i got a good deal on. i have the mounts/ rad/exhaust and linkage all worked out but i am reading that the 727 is longer than a 904 and that if the 318 had a 904 that it will work with my driveshaft. (#1)are all 904 transmissions the same length? (#2)are the flexplates different from a 904 to a 727?(#3) are the splines from a 67 727 different from a 73 904, in other words will my driveline slip yoke end slide into the 727 if i had the driveshaft shortened? (#4)is a 67 318 externally balanced and would i have to have a torque converter that is weighted? wow guys im really at a loss here for info. i hope im not making a mistake with the 67 318 and 727. any help would be wonderful,thanks

 

[duster360]

If the 318/727 combo is a complete setup with converter and flexplate included, I would just get another driveshaft. Or you could just get a 727 yoke and have your driveshaft cut and rebalanced. It would be a lot less headache. The 904 and 727 do have different yoke splines and the 727 is longer than the 904. What rearend do you have? You may be able to find what you need from members here.

 

[rumblefish360]

In sort, duster360 gave you the best advice and course of action. Just use the 318/727 combo. The /6 trans will not bolt to a S/B V8. Also, a S/B trans will not bolt to a big block.

The driveshaft shortening is a easy to do thing and it cost me about 60 bucks. As the guy with the 318/727 to include the driveshaft if possible, certainly the yoke. Though a new yoke can be purchased, it's money saved if he includes the yoke and/or driveshaft for you.

Upgrade your rear from the 7-1/4 to at least an 8-1/4.

I did this swap, /6 to 318, but did stay with a 904 trans. The swap of rear ends (As mentioned above) had me shorten the driveshaft. The rear ends, as they get larger in size also make shortening the driveshaft a must and shorter with each jump in rear size.

Possible tips here; ---> http://www.forabodiesonly.com/mopar/showthread.php?t=10508


Answers within the quote, in bold.

but i am reading that the 727 is longer than a 904 and that if the 318 had a 904 that it will work with my driveshaft.

(#1)are all 904 transmissions the same length?

Yes

(#2)are the flexplates different from a 904 to a 727?

yes, I do believe so.

(#3) are the splines from a 67 727 different from a 73 904, in other words will my driveline slip yoke end slide into the 727 if i had the driveshaft shortened?

No.

(#4)is a 67 318 externally balanced and would i have to have a torque converter that is weighted? wow guys im really at a loss here for info. i hope im not making a mistake with the 67 318 and 727. any help would be wonderful,thanks

All 318's are externally balanced.
You do not need the torque converter weighted if you keep the 318's torque converter. IF you use a 360 torque converter, there's an issue.

 

[Bulldozer]

thanks guys REALLY !! i didnt forget the THANKS button lol. a couple more things .. i read here somewhere that the spline count on a non lock up 727 CHANGED from 66 and 67 in 1968 .do you know if this is true. and can i use a yoke from ANY non lock up 727 driveshaft with the small u joints on my shortened driveshaft? OR are there any 727 driveshafts that will interchange with my 7 1/4 and 727 combo? i will be getting a beefier rear end but for now this is what i have to use.

 

[rumblefish360]

i read here somewhere that the spline count on a non lock up 727 CHANGED from 66 and 67 in 1968 .do you know if this is true.

This I do not know. But I do *Think* that the lock up's have a different spline count.

and can i use a yoke from ANY non lock up 727 driveshaft with the small u joints on my shortened driveshaft?

Big joint or small, there is a cross over U-joint that has the small 7260 joint size on one half and then the larger 7290 U-joint size on the other half. It was recently discussed here. I have one of these from Lakewood. Others make this joint as well.

OR are there any 727 driveshafts that will interchange with my 7 1/4 and 727 combo?

You will have to find an old old car for that combo. I'm not a numbers guy or a history buff on these cars. Just a hot rodder. IDK if there was ever a /6-727/7-1/4 combo available.

i will be getting a beefier rear end but for now this is what i have to use.

The cheaper (MUCH!) 8-1/4 will hold over 400 HP no problem. If your going North of that and/or beating on it, I would error on the side of caution and use the 8-3/4. There good up to and around the 700 HP level and strong enuff for everyday usage at this level.

 

[Bulldozer]

ok thanks rumblefish and im lovin your thread to very good stuff!!

 

[rumblefish360]

I wished I could have finished it, been more prepared for it. Now, in hind site, the next one will be much better. 400 into a /6 spot , 71 Duster.

(Same damn color too. LOL!)

 

[cudamark]

All good info.....I would add that the '67 transmission has a single wire neutral safety switch and therefore doesn't have any provision for backup lights. The switch can't just be swapped with the later 3 wire switch either as there are some internal parts that are different too.

 

[Bulldozer]

All good info.....I would add that the '67 transmission has a single wire neutral safety switch and therefore doesn't have any provision for backup lights. The switch can't just be swapped with the later 3 wire switch either as there are some internal parts that are different too.

do you know if my speedo cable will work with the older 727? thank you for the info!

 

[cudamark]

Yeah, the cable isn't a problem, it will thread right on the same way.