4 speed or 6 speed behind a Pontiac 400?

[T/A Addict]

I am wanting to put a manual back in my 69 and evaluating options before I buy. I have a chance to buy a T10 complete with everything needed for about 1k but the thought of just spending some extra to go T56 may be worthwhile. The cost is always a factor in my decisions but don't mind saving up a little longer if the added expense is worth it.

I know that nowadays T56s are easier to come by and all the accessories needed seem to readily available.

[silo84]

I would imagine your intended use or annual mileage would play a big part in the correct decision, (ex. if it's gonna be a race car I would go 4 speed to save the weight. if your gonna do the power tour, overdrive would be advisable)

Also to keep from too much floor pan surgery you might consider the TKO 5 speed as a middle option.

[cornfedbill]

I chose a Muncie because it is smaller and lighter, and gives me all the top end I need with my 3.08 rear. I did not want the extra weight or size of a T56.

If my car were more of a cruiser, I may have gone for the 6-speed.

Realistically estimate your annual driven miles and the type of miles. If you are going to be driving on the highway a lot or for long distances, you may want the overdrive. If it is mainly short trips or in town, it won't be an advantage to have overdrive.

[T/A Addict]

I live in a rural area so at a minimum I have to drive 55-60 for 30 minutes to get to town or 70+ interstate for an hour to work so cruising is priority pretty much.

[cornfedbill]

I live in a rural area so at a minimum I have to drive 55-60 for 30 minutes to get to town or 70+ interstate for an hour to work so cruising is priority pretty much.

You'll be happier with an overdrive transmission.

[rchaskin]

You'll be happier with an overdrive transmission.

Absolutely.

[T/A Addict]

ok then how would 4.10 gears do with a 6 speed?

[rchaskin]

I have a carbed 350 SBC at about 425hp, a LT1 style T-56 (2.66 1st, 0.75 5th & 0.50 6th), 26" tall tires and 3.73s.
I really like the combo. I don't use 6th until I am rolling 55 or 60. I am turning 1900rpm at about 75.

The close ratio magnums have a little tighter 5th and 6th.

Lots of people run 4.10s.
Based on past forum responses, It looks like most are in the 3.70 to 4.10 window.

There are lots of gear ratio calculators online.

[BonzoHansen]

There's more than 1 T56 out there. So a rear gear selection depends on which version of the t56 you have. Tire height comes into play as well.

I have one out of an LS 4th Gen car matched up with 3.90s & 26" tires and I think they're perfect for the car,

[T/A Addict]

Ok I'll have to research the better T56s for my application then. As far as the rear gearing I currently have 4.10s with 275/60 15s which are 28" tires so just trying to not swap them out if not needed. The tires will be changed with the final build but that is what's on it now.

[1985olds]

ok then how would 4.10 gears do with a 6 speed?


I have a tr6060 with a .57 6th and 4.10s and 25.6 inch tires. 80 mph is 2500 rpm.

[T/A Addict]

So would a TR6060 from a GT500 work?