Rockwell T221/SM465; Rare T-case?

['68OrangeSunshine]

I got this transfer case at my favorite junkyard. I thought it was a 465/205 set-up, but after finding and cleaning off the ID plate, it says it's a Rockwell Standard T221 N6, Ratio 1.94, Serial 7 68 0309. The 4-speed married to it has casting numbers:
H 17 8
2
GM
3901127
The rig has a 10-spline output shaft.
I checked the tranny's casting numbers against another 2WD known 465 I have and they were the same, except for the first line [date] D 29 8 = April 29th, 1968. so the unit with the 4WD t-case was cast on Sept 17th 1968.

Since '68 was the first year of the 465 and [about] the last year of the 221, there must not be too many of these T-cases around.

I am thinking of a project blazer, I call the "Phantom of the Junkyard." It started with a '72 Blazer rolling frame w/rusty tub, roll bar and doors -- and not much else. A buddy donated a '72 front clip doghouse to get it out of his yard. I have a couple of 292 L6 cores kicking around. I acquired the rare 292-only 4WD crossmember from a board member, now I have the transmission and transfer case. I'm not sure what's still in the differentials. This will be a long term basket case project.
Originally, the idea was to build a mirror image of my '71 Jimmy [350, 465/205, Factory posi 3.73 12-bolt rear, D44 front] so I could cannibalize components to keep the good one running. Now it's morphing into its own personality. The rolling frame lost its 2 mid frame transfercase crossmembers long ago. I could try to get some from a junkyard, or fab some new ones out of steel tubing -- flattened and drilled ends and sectioned struts in between.
I can copy the factory skid plate, too.
If the 221 has a different spacing configuration than a 205, I can mount it where ever it needs to go. I'll need new propshafts anyway so custom ones will have to do. Maybe I could cap it off with a half-top, seems to be the new K/5 fad-- and fab a mesh screen for a tailgate, so the dogs don't fall out.
All I need is a lot more money.

[Yukon Jack]

The Rockwell T221 was used through the 1969 model year. My 69 K20 had a Rockwell T221 married to a manual three speed. I have since changed to a SM465. I have a spare Rockwell T221 and SM465.

There aren't tons of these out there but not exactly rare either. Hard to get parts for the Rockwell, but you still can get some stuff. The adapter can be hard to find.

The Rockwell + adapter + tranny is the same lenght as an NP205 + adapter + same tranny.

The Rockwell is gear driven like the NP205 and has the same gear ratios. Just as strong, just older IMO. If you tear yours apart, make sure the spline coupler is in good shape, they can wear out.

The couplers are hard to find at a good price.

When I did my swap to the SM465, luckily I found that I could have the existing one cut down to the correct size for the adapter for the SM465.

[qksilver]

Is it possible to get a picture of that 292 crossmember. I bought a 67 Chevy 1/2 4X4 that came with a 6 cylinder and now has a V-8. I was going to restore it, it has to be rare. If it has the 6 cylinder crossmember I will find a 6 to put in it. What 6 came in a 67 chevy 4X4.
Thanks,
Steve

[1969 GMC]

Just make sure the Rockwell is in good shape, and the sleeve too. My '69 GMC K/2500 came with one behind the 465 stock. It ran low on lube because the rear output seal went bad, and this caused the input bearing to explode causing the t-case to lock up on me at 55 mph (bearing parts in gears Im guessing). It was not fun, and made me bitter towards the Rockwell case.

If you take the Rockwell and NP205 and put them next to each other, you will see which is a better designed and more heavy duty case. From what I've heard the Rockwell input bearing starving of oil is not uncommon because its so high up.

When I tore mine apart the sleeve connecting the tranny and transfer was toast. The splines were almost totally worn off, and were sharp to the touch. The rear output shaft of my 465 is toast, but interestingly enough the T221's input shaft looked brand new. I guess this also happens with the 10 spline Np205's. This is one area Ford's got us beat in, they were always either divorced or 31 splines with the tranny mating directly to the transfer.

I am done ranting now. Just check and make sure the Rockwell, sleeve, and 465 output shaft are good shape.

['68OrangeSunshine]

QKSilver: If I ever figure out how to use the camera in my cellphone and import it to my laptop, I'll shoot you a pic of the 292 crossmember. Basically it's diagonal. Since the 292 has a forward passenger side motor mount, while the drivers side mount is still in the middle, this configuration is necessary.
On a 250 the mounts are symetrical, on the 292 the fuel pump and motor mounts swap places. My theory is the forward mounting is to counteract the greater torque of the 1.75"-taller 292. GM never bothered to explain why. GM trucks in '67 model year could come with a 250 L6 or the 292 could be optioned. My '68 C/10 was originally ordered with a 292 and 17.5" x 7.00 rims & tires. On the C/ series [2WD], the engine mounts bolt directly to the frame, on the K/ series the extra crossmember is needed.
I think the 250 uses the same crossmember as the V8s [SBC at least.]
Yukon Jack + 69 GMC: I'll have a machinist check out the transfer case. A rebuild kit I priced at some website, stated about $300 for a T221 kit! I don't think that included the SM465.

[toolman]

I know this thread is a few weeks old, but seen it while searching for fluid capacity for the T221 Rockwell and SM465. I assume the plug on the transfer case about 2" above the drain plug on the drivers side is the fill hole ? Does anyone know for sure ? It just doesn't seem like that gives it much fluid capacity if it is...
Also since it doesn't look like it holds much fluid...what's everyones thoughts on jacking the drivers side up a bit when filling to get it slightly overfull, since it seems that rear bearing starvation is a problem ?

[Yukon Jack]

That is the fill plug, the gears throw the gear oil around and keeps it all lubricated. I don't see any need in trying to overfill it.

[toolman]

Cool, thanks....kinda figured as much...just wanted to be sure on the fill hole so I didn't burn it up.

[70BLAZERX2]

Anyone have a coulper for the rockwell T221? I am in need of one here..

I know its an old post..but....I need one..

[qksilver]

yes it's an old post but brought back memories!


Steve