Would gears solve this

[1LoC10]

Just curious if gears would solve this problem, or is it just because its a 3 speed...
I have a 350 with a 3 speed on the column, I dont know what gear it has but im assuming its stock.... the prob is the truck is wound out doing 45, it just screaming, and if I let of the gas its got the semi engine brake sound going on... now is this just cause its a 3 speed? or would it help if I put in some 4:11 gears, or should I switch to a 4 or 5 speed?

[4x4Poet]

3 spd & 4spd transmission both have direct drive high gear (1:1 ratio). Is this your 69 SWB? 2wd or 4x4?

If you have a multimeter, preferably analog sweep needle, hook it up for tac function and run the leads back to the unit in the cab so you can verify the rpm at speed. Be sure to route the leads so that they don't get caught in anything like the fan, alternator pulley, etc.

[1LoC10]

its 2wd and yeah its the 69.. I dont have a meter though

[special-K]

You probably have 4.10s.Was your truck a 6cyl.originally?Just about every 6cyl/3spd I`ve seen had 4.10s.Only adding O/D will help in the transmission dept.Going to 3.08s will let it fly/lose some bottom end.3.73s are a happy medium,still kinda low for hiway without O/D.I`m putting 3.40s in my shortbed that had 4.10s.I just don`t like 3.08s and 3.40 is as high as I want to go.They still have grunt.

[motocrosschump]

I thought the base rear end was 3.73's

[NewKid]

I can only talk about what I have in the 83 with the 350 4 bolt with th400. This set up was put together as tow package. It has 3.73's in the rear and a 2.48 ist gear in the trans. Not to good with the gas milage but good low and torque with A nice cruise speed. The th350 has 2.52 1st gear which is a little bit lower then the th400. Someone was using 3.23's and had lots of high end and great gas mileage but not enough torque in the low end. It all depends on what you would use the truck for the most. gear it for that purpose.

[67chevemall]

3:08's if you like the highway 4 sure.

[JAKES 68GMC]

Wow only 45? That makes my V6 seem FAST!!

[1LoC10]

I have no idea what the origional engine was, it doesnt say anything about it on the glove box sticker, unless you can get the info from the vin?
Well when I bought the truck it had a trailer ball on the bumper and it has a whole bundle of wires all wraped around the frame... so I assume they where for trailer lights and stuff... so maybe it was set up for towing... it drives ok, but it just feels like when you drive in 1st how when you let off the gas it pulls back....maybe ill just look into an auto with overdrive, that might make me happy

[Palf70Step]

Most of the 6/3 speeds were 3.73 or 4.10. I think it just depends on what year. My 70 was a 6 with 3 speed and 3.73. I could run all day at 70, but it was winding, but not screamming. Going to 3.08 will help with your top end, but with a 6 and 3 speed your low end will be gone. If you don't pull, haul much, or race (none of us do that ) your truck it would work out pretty well.
Even with 4.10s, you should not be screamin at 45 MPH. You may have other issues besides your gear ratio (clutch slippage for one) that is causing the indication. First off you need to make sure the speedo is accurate, which is very possible that it is not if the rear end or tranny has ever been changed out. You may be doing alot faster than 45.

[1LoC10]

Well im def not going alot faster, Im staying with everyone else...lol, Could it be that its the stock tranny and that its just not enough for a 350?

[Palf70Step]

The tranny was the same V8 or 6 for the 3 speed. It will definitely hold up and work. Iasmd not familiar with how low you can go with a sotck rear end, but if some one set you's up for serious towing it may have even a lower rear thatn a 4.10. with a 4.10 and a non OD tranny you should probably be doing 65ish at maybe 3700 RPM range. I'd say you need to verify the accuracy of the speedo before you do anything else.

[Americanrider]

Pop the rear diff cover and do a gear oil flush & check the ratio... sounds like the 4.56's I have under my 67K20. That will give you a starting point to work from. It would help if you could lay your hands on a cheapie tach to hook up for a test drive. What tire size are you running?

[1LoC10]

thanks for the info, I dont have a working tach but its def in the 4000's driving... ill look more into, but im pretty sure it was set up for towing

[1LoC10]

255/70/15 on all four corners

[Longhorn Man]

without a tach, you can't be sure what you're spinning. is this your first older non ovverdrive vehicle? Is it your first louder exhaust vehicle?
If your VIN starts with CE, then the engine was originally a 307. If it is a CS truck, then it was a 250 inline 6.
Assuming your truck is a 1/2 ton, the 3.73 gear was standard on both CS and CE trucks if it had a 3 speed.
If we are talking 3/4 ton, then a 4.56 gear was standard with a 3 speed in both CE and CS trucks.
Now granted, we are all assuming that it is original, and it may well not be.
Get a tach. I have a feeling you'll be shocked at how low your RPMs really are. Gearing wise, every one of these trucks built, inline, v-8, 3 speed, 4 speed.. what ever, should be able to do 100 MPH without hitting redline. I will exclude 4.56 and 5.13 geared trucks from this, but all 4.10, 3.73, and 3.07 gear equipped trucks should have enough RPMs to get to 100, so at 54MPH, there is no way you are spinning 4000 RPM, that would make your truck redline at about 50 MPH or so.

[JAKES 68GMC]

with Andy about the exhaust. I've got straight pipes that exit under the cab on my truck, and turning 2500rpm sounds like a freight train on steroids.

BTW Andy also include GMC V6's on your exclude list. Theres no friggin way my trucks gonna do 100mph with 4.10 gears.

[Longhorn Man]

good call.

[special-K]

My K/20 with 400,4.10s,and 33" tires is turning 4,000rpm @around 88 mph.

[hgs_notes]

My truck came withthe 3.73 rear end and a 3 speed. It would do 55 in 1st gear. I don't care what the rear end gears are, unless you're running 12" trailer tires there is no way it is winding out at 45 mph in 3rd gear. With my current set up, 275/60-15's on back, 3.73 rearend, it runs about 2800 rpm at around 60 mph.

[JAKES 68GMC]

That would be cool to go 55 in 1st gear. Not very good for torque or pulling though.

[Gray Ghost]

I think it sounds like 4.56's as well. My CE came with a 350 according to the glovebox decal [an option]....mileage sucks at 12-13, but it will be hauling lumber and a trailer at some point, so it's probably best I keep it in there.

The motor in mine is running around 325-350 hp and tachs around 3k at 60 as far as I can tell [bad tach I think cause it jumps around a bit]. It has plenty of leg left at 70-75 mph.

[1LoC10]

The vin starts with a CE... Well I could be wrong about the RPM's but I dont care how loud the exhaust is, when you let of the gas it shouldnt throw you into the wheel and drop speed that fast, I didnt say I couldnt go any faster, I had it up to 70 on the express way.. I can't explain it I guess, but put you truck in first gear and floor it down the street and let off the gas... thats how my trucks acts in 3rd..LOL

[special-K]

That`s how low gears are.It`s "engine braking".It would be unusual to have 4.56s in a shortbed w/12-bolt rear.They,re prolly 4.10s and you could swap to a 3.08 rear to get more "lunge".But,if you`re considering an O/D tranny,I`d do that first.You may be happy to keep the "pullin`power" yet gain the "cruise speed".

[Gray Ghost]

Maybe you don't have third gear at all. That just isn't right for it to be acting like that, even with 4.56 gears in third it shouldn't do that. You better get everything checked out, sounds like something is terribly wrong.