I'm buying a '68 slant this weekend and the guy said I need a flex plate and torque converter from a '68+ car. The dilemma: I have a '65 drivetrain, and a '73 drivetrain. Will the '68 engine bolt to the '73 flexplate, torque converter, and 904? Or to my '65 set? I appreciate the help guys!

-Ryan

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

Don't quote me on this, but I think that 1968 is when the cranks changed from a small pocket to a large one. From the sound of what the previous owner said, the 1968 should mount to the 1973. Wiser Folks will chime in.... unless they are all out racing!

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1964 Dart GT

Crank pocket change occurs in 1967 so:

You can bolt any 1968-1987 slant six up to your 1965 tranny and torque convertor if you get a bushing from Doc or Pat Blais....the reverse is not true (that's a crank change or custom torque convertor for those onlookers wondering about it).

So yeah, a 1968-1987 flex plate will be needed if using the late engine... Also note that you may need to work a few things as the 1968/1973 tranny is a newer beast than the 1965 and you'll need some linkage and other bits to make it work correctly...

-D.Idiot

You need a flexplate for the year range (67 and older, or 68 and newer) of the engine.
You need a torque converter for the year range of the transmission (67 and older, or 68 and newer).
If using a 67 and older trans/converter, you will need an adapter bushing to go into the end of the crank. This bushing is inexpensive, and available from Myself, Doc, or tfpatty.
If the car is a 65, it would be easier to keep the 65 trans, and converter, using the 73 flexplate and the adapter bushing for the crank.
The 73 trans will bolt up to the engine, but require mods to adapt to a 65 car. The shifter setup, speedo cable attachment, and front U-joint (B&T joint on the 65) are all different.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thanks guys, I have a '69 coronet slant donor car, which is where the '73 drivetrain is coming from. So with linkages and stuff like that I have no worries. Also, I'm switching to a aftermarket floor shifter, so the shifter linkages aren't a problem.

-Ryan

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

Driveline/tranny/engine would be OK in that range. Just be aware that in 1973 Mopar changed the B-body and went to rubber isolated K-members and I think on the rear springs as well...so if the '69 was converted using 1973 suspension parts be aware the spindles might be taller (like the F-body vs. A-body, this is why 73-76 A-body spindles are hard to get as they are a bolt in for 66-72 B-Body) and a few other things will need to be changed to make it work.

Hopefully the drive line is a full metal tube as the late models sometimes had the rubber lined tube in tube drive line to dampen vibrations (but would slip if you put a lot of torque on them).

You will probably need a specific (1967? Threaded end on speedo and large nut on tranny) speedo cable to go from the modern 904 to your speedo as well.

Good Luck,

-D.Idiot

I'm not running a speedo, and I'm keeping the suspension in my '65 car the same as it is now. I'm just switching engine and tranny, driveshaft probably as well, unless I can switch the snub (attaches tranny to drive shaft) from the '65 to the '73.

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

The output shaft on the '65 should be threaded to accept a nut to retain the flange, 1966+ they are splined an no threads for the nut, you will need the driveshaft and the slip yoke.

-D.Idiot

The 73 driveshaft may or may not work (length), depending on the vehicle
it came from.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

The assumption made here is the '69 B-body he's pulling the parts from was retro'd with the parts from a '73. Charrlie would be correct because of the rear axle and wheelbase options, the'73 most likely had an 8 1/4" and it might need to be cut down to fit I have a couple of B-body drivelines from 70's chargers they range about 58-59" long (they were from 318/904 8 1/4" cars) so he should be able to ball park it from there the yoke would be able to take up another inch of slack if it's just that short.

-D.Idiot

I have a similar problem. We just put a 67 slant six in our 73 dodge dart Swinger and flex plate and torque converter won't fix right for the 73 transmission to go on. So do I need to get a 67 flex plate and torque converter for it to work? Also will the 73 transmission go on it?

The bigger problem is the hole for the converter pilot in the 67 engine is smaller than the 73 torque converter pilot.

I am pretty sure that a 66 or 67 torque converter will have the small snout to fit your 67 crank, AND the large trans spline to fit your 73 trans. Anything 68-up or 65-down will not work. A flexplate from a 67-down Slant automatic (any year) will fit your crank. The converter will be the hard part. Maybe Charrlie_S would have a converter or a source??

Best of luck!
Lou

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Home of Slant6-powered fun machines since 1988

Your options are:

• a custom-made torque converter ('67-down small-nose front, '68-up rear)

• A pre-'68 torque converter, and the input shaft and associated parts of your transmission replaced by '67-down pieces

• Enlarge the counterbore at the rear of your '67-down crankshaft to fit the '68-up torque converter

• Install a '68-'76 crankshaft in this '67 engine

• Install a '68 or later engine assembly

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The only way(s) to put a 67 or older engine to a 68 or newer 904 is:
1) special torque converter with the small pilot to fit the early engine and the large internal splines to fit the later trans. (Best way)
2) remove the front section of the late trans, and substitute the front section of the early trans and use the early converter and flexplate. (makes a weaker trans)
3) Swap to a later 68-76 forged crank in your early engine, or have the "pocket" in the end of the early crank enlarged. (Requires engine dissasembly)

Dacco used to have rebuilt converters for this application. Don't know if they still do, as they were bought by another company.
Andre at Edge racing converters was building these for me, but, again I don't know if he is still doing them.
https://edgeracingconverters.com/

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225