LUVTruck.com

Does anyone know if there's a direct drop-in differential for a '79 2WD LUV? I drive mine about 80 miles round trip a day, and those 4:11s just aren't the right setup for that. I'm hoping for something in the 3:50s maybe. I don't want a 5-speed.

Look for an '84 P'up, 1.9 4sp "MPG" model, should have a 3.43 ratio third that will bolt right into your housing. If you can get the driven gear from the end of the speedo cable also, otherwise your speedo will be off.
Some diesels had this same rear ratio also.
An alternate- '78 LUVs with auto trans had 3.73 gears.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

Thanks for the great info. I should also ask if my axles will fit this diff.

Yes the axles will fit.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

I know your problem, my stock LUV would run out of oil at the 70-80 mile per hour speeds neccesary here in So CA! And it got worse when I first wapped to a Buick 231, I had to keep it below 60!
So here are a couple of suggestions, I did a lot of measureing and I found that a Ford 8" rear end out of a 302 powered Maverick or Comet from the 70-early 80s would fit right in, these are only two inches wider than a stock LUV and come with 3:00-1 gears!! These are the narrowest 8" rear ends made by Ford. (54") I just ground off the old mounting pads and had some new ones welded on, made up a new driveshaft and had a Great Freeway Cruiser! I can check on a business here in So CA and find out how much one of these will cost if your are interested? Course you would have some shipping costs.
Or you can do as suggested and use one out of a diesel powered LUV. (3:42-1) I have one of these if you are interested, look at the classified ads on this site.
Aome guys have reported used S 10 rear ends too, but I have no information on this. For more info pls contact me.

Only the 2wd 4-speeds had this ratio. Most were 5-speeds, with 3.72 rear ends. The 4wd LUVs had 4.10 gears.

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

Can anyone help with the ring gear size & corporate axle ID on the series 9-10 LUVs? Is it a GM 10 bolt, an Isuzu 10 bolt, what is the ring gear size (7.5" or 7.625"), etc. I'm planning a diff change, and want to get all the right gaskets & rebuild parts if needed.

All LUVs came with the Isuzu corporate 10-bolt, the GM rear came in '90-'95 US-built Isuzu pickups.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

I got a 91 pup with a 2.6 and a 12 bolt rear so that rear is a GM ? How strong is it.?

No, that's a Pickup.

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

smokey-
Only pickups with the 2.3 engine came with the Isuzu or GM 10-bolt, trucks with the 2.6 or v6 came with the Isuzu corporate 12-bolt. It's a fairly beefy unit, close to a Ford 9-inch in strength.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

I plan to change the differential gears in my '79 2WD 4 speed for less highway rpms. The more research I do, the more confused I get. I've heard that LUVs with automatics have 3.73 gears, and 4 speeds have 4.10; if you go to the 1979 or 1980 owner's manual .pdfs on this site, the last page says just the opposite. Is that a factory typo?

Assuming I have 4.10's, I'm looking for a good 3.73 center section, near Portland OR.

Try searching on line at car-parts.com, type in your truck info, try axle assembly rear with housing for the part, use distance for how you want to search. This will give you some idea of where to start looking. Since all you need is the 3rd member you may be able to get it for less than the entire axle assembly.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

I just checked the rear end ratio on my 81 formerly diesel powered Luv and found it is a 3:42. This truck came with a 5 speed behind the diesel, just fyi.

the only luvs or pups to have that combo where sold in CA state with the mpg+ package,
the mpg rating of the 5sp 3.42 is lower than the 4sp 3.42
3.42s with the O\D gear is just to long of legs, but is about right in 4th depending on tire size used.

3.73, 4sp, and big tires, does much better than with the 3.42 gears.

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86trooperT/D 2.2
84 L\B 4x4Diesel LS 2.2
84 S\B 4X4 gas rust bucket 1.9
86 L\B 4X4 gas 5 speed 2.3
the twins, 81 pup and 81 LUV both are diesel 2.2



The Energizer Bunny is trying to keep up, and is starting to gasp for air!!

I picked up a 3.73 diff last weekend, and it's going in today. Next is a speedo gear swap, and I remember seeing some great close-up photos on this site of how it's done, but I sure can't find 'em now. Anybody remember what thread that was in?

Good information from Trooper Diesel, when I had the stock diesel engine in my 81 Luv, I could not use 5th gear, except coming off a long hill!! There was not enough power to pull the truck on level ground!! And I was advised by several people that I should never let the engine lug down below 50 MPH, or the transmission would soon be toast!!
I don't have a history of my truck because I bought it in Portland off e-bay several years ago.
The 3:42s really work good behind a sbc and a 700R4 o/d trnsmission! 80 mph is about 2150 rpms, and it has plenty of git up and go.
Good luck,