gearbod identification ?

[beddiecamper]

Hi can anyone identify a holden 4 speed box in a 76 cfl motorhome casting number 9938391. thanks mark.

[able]

looks like 9938391 is just the part number of the side plate and has nothing to do with it...
http://gallery.oldholden.com/HQ_SS/Tech/Gearboxs/Aussie+4spd/Side+cover+Late+9938391.jpg.html

cluster number seems to be the go... apparently found on the cluster gear.

Firstly, the use of the terms M20 & M21 & so on, is very confusing. The 1 code number can refer to more than 1 type of box, so it’s better not to rely on them. For instance an M20 is also an Opel 4-speed, an M21 is a Saginaw, the M22 is another Saginaw & M22 is also what GM in the US call their Hi-Torque Muncie ‘Rock-Crusher’ box. The box in the XU-1 is called an M20 even though its ratios are closer to what we normally call an M21. See what I mean!!

Anyway there are 5 different ratio sets available in the Aussie 4-speed. They are:-

3.05/2.19/1.51/1.00 (Cluster Part No. 2813496) This is the most common version (normally called the M20) & is available with both 6 & V8 front shaft lengths.

2.54/1.83/1.38/1.00 (Cluster Part No. 2813497) This is probably the 2nd most common box & is standard fitment behind 308/5.0 V8s (normally called the M21) & is usually only seen with a V8 length front shaft, although there was a 6-cylinder version homologated as a alternate choice of ratios for the LJ XU-1.

3.74/2.68/1.68/1.00 (Cluster Part No. 2820694) This is the ‘wide ratio’ box (normally called the M22) that is usually only seen in 6-cylinder HQ-WB One-Tonners. It was only ever factory built with a 6-cylinder length front shaft, but since the clutch gear is the same as an M15 3-speed box, you could use an M15 V8 front shaft & make a V8 M22 if you really needed one.

2.54/1.83/1.25/1.00 (Cluster Part No. 2823899) This is the box that is often wrongly referred to as the 6-cylinder M21, when it was actually called the XU-1 M20 (by GM-H). It was standard issue in XU-1s (with a 6-cylinder front shaft, obviously) but the same ratio set was also homologated as an alternate unit for racing for the L34 (with a V8 length front shaft).

2.54/1.65/1.25/1.00 (Cluster Part No. 9939484) This is probably the rarest box of all, as it was only seen as an homologated alternate unit for the LJ XU-1 & the LH L34, with their respective 6-cylinder & V8 length front shafts.

Another common myth to dispel is that there is no difference in strength between any of these boxes, they all use the same bearings & casing etc. A V8 M21 is no stronger than a 6-cylinder M20. The M22 is not stronger just because it’s a One Tonner Box. Also, as mentioned in an earlier post using the ID grooves on the front shaft is not reliable.

Hope this adds to the confusion.

http://www.gmh-torana.com.au/forums/index.php?showtopic=2393

[BlackBedford]

G'day

From what I have seen the CF 4 speeds were M22 type but as far as I am aware they were only optioned behind a 202. If a reconditioned gearbox was fitted it would unlikely to still be a M22. If it is an M22 then 1st gear will be very slow.

Regards