I plan on swapping the '96 over from the 4T60 to a 4T65 that I sourced from a '98 Bonneville SE. I would really like to convert this transmission over to the HD version and use 3.39 Overall Gear Ratio. However I have a couple of questions.

1. Are all HD diffs a 3.29 Ratio Diff?

2. Do I need to swap the ring gear in the non-hd 4t65 at the same time as I swap the diff? Which Ring gear would I need to source.

I plan on installing the 4T65 HD upgrade kit from ZZP and their 7/8 chain kit too. I am just trying to make sure I don't miss anything during the rebuild.


Thanks

_________________
Dave

INFO FOR CONVERTING SE TO SSE BODY HERE=>>http://www.pontiacbonnevilleclub.com/forum/detailing-appearance/topic39372.html
http://www.pontiacbonnevilleclub.com/forum/performance-brainstorming/topic43633.html
2002 Pro Stock Pontiac Firebird**GM 399 Splayed Valve Engine
1996 Pontiac Bonneville SE/SSE **100% Transformation from SE to SSE Complete**Lowered 2.00inches too**

I can't recall exactly, but I thought you only need a ring gear change if you have a 4t60.

_________________
Boost addict


The Fleet:
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'97 Camaro - Top swap
'05 STS - V8, AWD, her DD
'92 Trofeo - Fair weather DD
'99 Montana - top swap 3800
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'92 Bonneville SSE
'87 LeSabre T-type
'67 LeSabre

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'84 Sierra Classic - Twin turbo 3800
'97 LeSabre - Top swap

RIP:
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'93 SE - L67

If memory serves, a stock 2.86 ratio or 3.05 4T65E will have the 35 Drive and 35 Driven gears, The 4T65E HD uses a 37 Drive and 33 Driven for an overall 2.93 ratio( This is the 3.29 Diff )

If you use the 35 Drive and 35 Driven with the 3.29 HD Diff, HD diff cover and HD axle you will have an overall 3.29, I would get the ring gear just to have it, but iirc the ring gears between the 2.86, 3.05 and 3.29 should be the same.

What exactly is in ZZP's upgrade kit? Be wary of them, they love to sell snake oil. The HD trans is in reality no stronger than the regular one.

_________________
-Car Guy Carl
"Penelope" - 2003 SLE - 247k Miles
"Sydney" - 2000 Honda S2000 - 98k miles

to convert from a Non HD to a HD you need the following.

HD Diff (3.29 ratio they are all this way)
HD Diff Cover
Passenger Side SSEi axle
PCM Programming to accept the 3.29 ratio

I "think" the sun gear that is inside the Diff is a different size, and you will need a HD Diff Sun Gear

I should have said make sure that 3.29 HD diff has the sun gear..lol


HD 3.29 on the left and Light Duty 3.05 on the right..