8.8 or 7.5 in 86GT??

Comatose · 06-03-2004, 09:57 PM

I'm getting ready to order the remainder of the necessary parts to install my 3.27 gears (it's got 2.73s now), and need a clear answer before I spend the $$. I've already got the gears.

Most articles I've read have stated that the 86GT was the first year the 8.8 was used. I've also heard/read a couple times that an 86GT owner swapped out their 7.5 for the 8.8.

I'd hate to get everything I need together, tear down my rear end only to find out it's a 7.5.

Can anyone give me a clear definite answer? I'm pretty sure it's the 8.8, but I have a small amount of lingering doubt.

stang_racer20 · 06-03-2004, 11:54 PM

Your right on there. 86+ Mustang V8's came with the 8.8" factory. Check out www.mustanggt.org, just to clarify it. Check your axle tag if it's still attached for the the rear end #. You can usually tell just by looking at it size wise, whether its a 7.5" or 8.8".

~The Jester~ · 06-04-2004, 06:49 AM

Easiest "rule of thumb" is that a 7.5 has a single bolt at 12:00 on the cover, an 8.8" has 2 bolts at 11:00 and 1:00

This should help you out.

http://www.nationwideparts.com/differentials.htm

codybear · 06-07-2004, 08:25 PM

Off the subject a bit, but can you post a picture of your in fullsize view? and is it t-tops?

Comatose · 06-07-2004, 09:59 PM

Sorry, I don't have a fullsize pic at the moment. The car doesn't have t-tops.

Comatose · 06-07-2004, 10:03 PM

After looking at the differential cover pattern, I found that my car does in fact have the 7.5.

Time to start looking for an 8.8.

06-09-2004, 07:19 PM

I thought '86s had 7.5 rearends. I guy I used to work with was building up his '86 GT and he too had to replace the 7.5 that came in it.

codybear · 06-09-2004, 08:44 PM

All I know is I have 2 mustangs and both have different size rearends, I measured and one is about 2 inches larger than the other, do they make a 6.5?

codybear · 06-09-2004, 09:07 PM

Heres a cut and paste from a website that sells rearends

"All 1979-85 Mustangs came equipped with 7.5" rear-ends (7.5" refers to the diameter of the ring gear). 7.5" rear-ends also came in all 1979-04 non-V8 equipped Mustangs. The stronger 8.8" rear-end debuted in 1986 and still rides under all V8 Mustangs to date"

Comatose · 06-09-2004, 10:08 PM

I've looked at two 86's, both with V-8s and they have the same differential cover pattern. I've also looked at a 98 1/2 ton Ford Van, and it too has the same pattern as my car. According to pictures I've seen in MM&FF, the rear end in my car is an 8.8, according to a previous link on this subject, the rear end is a 7.5.

I'm cunfuzzed.

06-03-2004, 09:57 PM	#1
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	8.8 or 7.5 in 86GT?? I'm getting ready to order the remainder of the necessary parts to install my 3.27 gears (it's got 2.73s now), and need a clear answer before I spend the $$. I've already got the gears. Most articles I've read have stated that the 86GT was the first year the 8.8 was used. I've also heard/read a couple times that an 86GT owner swapped out their 7.5 for the 8.8. I'd hate to get everything I need together, tear down my rear end only to find out it's a 7.5. Can anyone give me a clear definite answer? I'm pretty sure it's the 8.8, but I have a small amount of lingering doubt. __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

06-03-2004, 11:54 PM	#2
stang_racer20 Registered Member Join Date: Jun 2003 Location: Wisconsin Posts: 348	Your right on there. 86+ Mustang V8's came with the 8.8" factory. Check out www.mustanggt.org, just to clarify it. Check your axle tag if it's still attached for the the rear end #. You can usually tell just by looking at it size wise, whether its a 7.5" or 8.8". __________________ 92 Mustang GT, 347 Stroker(Forged Steel Crank/Rods-Balanced, Forged Aluminum Dished Pistons), Trick Flow Track Heat Intake, Trick Flow Twisted Wedge Heads w/ Stage 3 port/polish, 80mm C&L MAF, FMS 30# Inj., BBK AFPR, Trick Flow Stage 2 Cam, Trick Flow 1.6R Rockers, BBK E.L. Headers, Flowmaster Cat-Back, MAC CAI, FMS Pulleys, Griffin Alum. Radiator, MSD Pro-Billet Distributor; AOD, Dynamic 3300 Lockup Converter, B & M Super Cooler, B&M Ratchet Shifter; 3:73 gears.

06-04-2004, 06:49 AM	#3
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Easiest "rule of thumb" is that a 7.5 has a single bolt at 12:00 on the cover, an 8.8" has 2 bolts at 11:00 and 1:00 This should help you out. http://www.nationwideparts.com/differentials.htm __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

06-07-2004, 09:59 PM	#5
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	Sorry, I don't have a fullsize pic at the moment. The car doesn't have t-tops. __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

06-07-2004, 10:03 PM	#6
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	After looking at the differential cover pattern, I found that my car does in fact have the 7.5. Time to start looking for an 8.8. __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

06-07-2004, 08:25 PM	#4
codybear Registered Member Join Date: Sep 2003 Posts: 63	Off the subject a bit, but can you post a picture of your in fullsize view? and is it t-tops?

06-09-2004, 07:19 PM	#7
Simi Stang Guest Posts: n/a	7.5s I thought '86s had 7.5 rearends. I guy I used to work with was building up his '86 GT and he too had to replace the 7.5 that came in it.

06-09-2004, 08:44 PM	#8
codybear Registered Member Join Date: Sep 2003 Posts: 63	All I know is I have 2 mustangs and both have different size rearends, I measured and one is about 2 inches larger than the other, do they make a 6.5?

06-09-2004, 09:07 PM	#9
codybear Registered Member Join Date: Sep 2003 Posts: 63	Heres a cut and paste from a website that sells rearends "All 1979-85 Mustangs came equipped with 7.5" rear-ends (7.5" refers to the diameter of the ring gear). 7.5" rear-ends also came in all 1979-04 non-V8 equipped Mustangs. The stronger 8.8" rear-end debuted in 1986 and still rides under all V8 Mustangs to date"

06-09-2004, 10:08 PM	#10
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	I've looked at two 86's, both with V-8s and they have the same differential cover pattern. I've also looked at a 98 1/2 ton Ford Van, and it too has the same pattern as my car. According to pictures I've seen in MM&FF, the rear end in my car is an 8.8, according to a previous link on this subject, the rear end is a 7.5. I'm cunfuzzed. __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

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