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I recieved my new M551 book from David Doyle (Thanks ) and enjoyed it very much! I can't get enough Sheridan stuff! There was one thing in it that really got my curiosity going and I want to post it here and see if we can shed some light on it. This is in no way meant to be critical of David's book. I'm just very interested in the M551's history. On page 9 is a picture that says it is vehicle #24 being delivered in 1966. There are two things that threw me here. First you will note the rings on the end of the grenade launchers. The rings were a modification that I thought came out in the early 70's. Secondly you can see the external pull handle to open the driver's hatch from outside. This also was a modification that I thought came out around 1975. I'm curious what the sign says.

Below is a Sheridan in Viet Nam in 1971. It has neither of the stated modifications. So the mystery is if the above photo is 1966 then why weren't these mods put on all of the Sheridans?

Something of note on "#24" is that it originally had it's turret fan in the old location. A plate has been welded over the hole. This is only the second one of these I've seen.

I confess to being completely unfamiliar with external pull handles for the driver's hatch*. Now I'm eager to get home and check all my pictures.


*Then again, I ETS'd at the end of '73

Edit:
VISMOD "mine plow". Still learning new stuff about Sheridan's 38 years later....

Doug, In Germany they put this MWO on around 1975 IIRC. It was so they could rescue an incapacited driver. It's something I've always used to date photos.

EDIT: Doug, look at your picture on the other side of that driver's hatch and you can make out the external slave receptacle. This MWO came out after I ETS'd in '79.

Another photo of "#24" from David's book. The two red circles are the bilge pump outlets. We had problems with dirt getting in the slots and clogging up the bilge pumps. So at some later date the slots were done away with. The flat thing on the exhaust is called an "Exhaust Plume Diffuser". It was MWO #1 on the Sheridan. (Modification Work Order) Not sure when that came out though. Another thing I noticed is that the grill does not have a screen over it. I don't know why.
[img]http://www.com-central.net/modules/coppermine/albums/userpics/10924/normal_scan%7E1.jpg[/img]

Mark,
I have a copy of Org. Maint. Manual dated June '66. It shows the bilge pump slotted covers, not the exteranal driver release handle (which I never saw in service, for reasons we know). Only became familiar with the "exhaust plume diffuser" on later vehicles (ours were an artillery powder tube canister with the exhause outlet attached to the end, raising the whole affair about 2' into the air...not so much "diffusing" the plume, as getting it up out of your nostrils in heavy bush ).

I can't swear that I haven't seen the standard diffuser on older vehicles, but I certainly don't recall doing so.

How did the driver turret release handles come to be installed...from new beynd a certain date, or retrofit to all vehicles still in service?

I don't recall the "ringed" smoke dischargers either, nor do they appear on the fairly pristine ones we had in my Sheridan School class.

I'm not familiar with a driver's turret release. I think the M1A1 has something like that. But they did a lot for the 82nd AB Sheridans. TTS, new grenade launchers, new driver's panel. Maybe it had something like that. I'll have to check. I've got the -10 on CD.

- MarkHolloway

I'm not familiar with a driver's turret release. I think the M1A1 has something like that. But they did a lot for the 82nd AB Sheridans. TTS, new grenade launchers, new driver's panel. Maybe it had something like that. I'll have to check. I've got the -10 on CD.

Mark,
I mis-spoke, typing too fast. Meant "driver's external hatch release" thingy. Probably thinking of the way it rotated compared to other hatches one usually thinks of.

This shows the release:

Got my book today,

Worth every penny and then some just for the pictures.

Great work David

I'll try to shed a little light on this....

From the registration number, the delivery date of the vehicle was determined. The "shortly after delivery" statement is from a note in the file at the Ordnance Museum - a note written at an unknown time and by an unknown person.

That being said, I know infinitely more about 2 1/2 ton G-742 trucks than I do any other military vehicle. And I have copies of the test reports and correspondence between the army and Reo regarding what has come to be known as the air shift front axle. The correspondence dates from 1952-53, the test reports from 53-55 - and this improvement first appeared in production vehicles in 1971-72...with tens of thousands of trucks delivered in the meantime.

Hence, I'd not bet my life on it, but it wouldn't surprise me if Aberdeen was testing these Sheridan mods in 66-67, yet they weren't fielded until a decade later.

Best wishes,
David

PS: Joe and Mark, thank for your kind words.

David,

You beat me on that one, I was going to say the same thing. There were so many mods made for the M1 that took many years before they were officially put into production and then MWO applied to older models. Many MWO's were to upgrade older fleet models that were dated years after production models had them. Good case in point is the conversion from M73/219 MG to M240. The M60A3 was produced with the M240 whereas the M60A1 had to be upgraded with an MWO which was dated in the 80's. Budgets play a lot into this too.

I'm keeping notes on this whole discussion for my M551 project.

- Joe_D

Good case in point is the conversion from M73/219 MG to M240. The M60A3 was produced with the M240 whereas the M60A1 had to be upgraded with an MWO which was dated in the 80's. Budgets play a lot into this too.

Just a warning, Joe, shot-across-the-bow thing...you're risking a ritual "banning" just for invoking the memory of the M73/219 MG.

Yes, the infamous M73/219.

Was told all the Horror stories by TC's and Gunner's when I was a young troop. Lucky not to experience them.

One named SSG Boggs told me the Nomenclature for the M219 was derived by multiplying it's predecessor, the M73, x 3, which was how much worse it was.

I actually got to work on one (M219) at Rodelheim in W. Germany. I couldn't believe they actually made that thing. What an idiotic concept and design.

David, Good theory. I never thought of it taking ten years to get a mod to the field but that's certainly plausible. It would explain it all.