changeover questions

[fryedaddy]

i now have my c6 out of my fe 66 comet.im going back to a toploader 4 speed,wide ratio,small imput.question 1-will my c6 driveshaft yolk fit the toploader? question 2-will my c6 crossmember work on the toploader?

[Nightmist66]

If the Toploader has a small output to match the input, then no. C6 and big out TL have 31 spline. Small out TL is 28 spline. The crossmember should work.

[GerryP]

For Fairlanes, crossmembers are based upon the engine, not the transmission type.  Your FE crossmember is the same for automatic or manual.  Smallblock and six crossmembers are different.

As above, C6 and big in and out toploaders use the same 31-spline yoke.  Small in and out and C4 are the same 28-spline yoke.

As for the transmissions, the long tail toploader is the same length as the C6 at 27".  The short tail is the same length as the C4 at 24".  This is important to know when it comes to the driveshaft.  Your case may be different, but if you replace a C6 with a long tail toploader, you don't need to replace the driveshaft except the yoke if necessary.

[fryedaddy]

the crossmember i took off the c6 is real beefy and has extra medal near the bolt holes and all over,i have a 2nd crossmember that is the same size and same bolt pattern but it is much thinner and lighter but other than that they are the same.my drive shaft yolk went way up in the c6,it was borderline too long.it may work or it might be a inch short when i put the 24 inch toploader in.

[Keith M]

The trans crossmember differences that I could tell, the big block cars do appear to be 2 pieces of metal stamped together, I have one that I got out of a 250 69 ranchero, and it it was only one layer of metal stamped.

Keith

[Henrysnephew]

Keep in mind that some small input toploaders have the big 31 spline output.  Early 70's with 351C applications comes to mind.  Randy M

[cjshaker]

Keep in mind that some small input toploaders have the big 31 spline output.  Early 70's with 351C applications comes to mind.  Randy M

I was not aware of that, and have never seen one from the factory that way (not at all saying you're wrong), but given the age and likeliness that things have been worked on over the years, it's wise to always check, because someone could easily change the input shaft.

[Henrysnephew]

Keep in mind that some small input toploaders have the big 31 spline output.  Early 70's with 351C applications comes to mind.  Randy M

I was not aware of that, and have never seen one from the factory that way (not at all saying you're wrong), but given the age and likeliness that things have been worked on over the years, it's wise to always check, because someone could easily change the input shaft.

Yes, lot's of mix-'n-match toploaders out there and one never knows.  I have a small-in, big-out RUG-BG1 on the shelf though, which was spec'd that way by (uncle) Henry.  Randy M

[fryedaddy]

i have another driveshaft with the 28 spline yolk and it is about 3 inches longer than my c6 driveshaft,so i should be able to get one of them to work.and my 4 speed is small in and output.  QUESTION-will the 4 speed free up any hp verses the c6?

[GerryP]

Yes.  But unless you are class racing, it won't make a difference you could notice.  The Four speed is a different driving experience and that's what you "feel".