Have ran the same input shaft since 2009, probably 1500 or more runs and it was used in 09. Pg turbo spline standard diameter

Who's had good luck with what? Looking at 300m

I am not sure I wouldn't get exact same piece as what you have. Unless you are planing big power increase.

Now that said. If I was buying new one I would buy strongest thing madxe that will work with your pump and converter. I never liked HP ratings. Why buy one based on how much power it will take. Just makes sense to overkill here. PIA to pull and check.Odds of you catching it before breakage slim. Could cost lot more if takes out the converter or damages pump.. JMO sorry no real input one which is best, but sure others will have.

Your old one owes you nothing, get it out while the getting is good

Cant go wrong with either Coan or Sonnax. Defiantly 300M material if it is an option

Personally, i would put a vasco style ringed input shaft in it. Yes they are several hundred dollars more, but the input shaft takes a lot of abuse.

Jeremiah is correct, the Vasco material is the strongest, 300M a close 2nd

Here is a simple example of strength differences between manufactures and materials.

My situation is apples and oranges to the OP

A couple years back I could not get an input shaft to last more than 20 runs in my blown TD. I was running a 1 inch ringless Coan and never ever broke one but would twist it bad enough that I would have to beat the converter off the input because the shaft was getting stuck in the turbine splines in the converter. Coan uses a made in USA Aerospace material, I believe it is Vasco but I may be wrong.
I was in desperate need of a input and Coan was out of stock, I bought the so called equivalent TSI shaft with what I believe to be China steel, it did not make it 5 runs without twisting way worse than the Coan ever did, it would of broke for sure.
In the off season I upgraded to the Sonnax 1.125 shaft and have never twisted it since,

COAN…….FTW..

We ran a 1.125 shaft way before anyone did ,before Sonnax had one on the market. Sonnax was just developing their 1.125 shaft a year into us having one. They had one fast NMCA racer can't remember his name running it and asked us if we'd like to run it for development, we already had one we couldn't break with the main man tuner from Pro-Line doing the tuning. Same tuner who tuned the JEGS pro mod to a couple NHRA championshps.

Before the 1.125 we ran both Coan and TSI ringless and broke em both around 17-18 laps. The Coan twisted and we'd ring off the TSI.

TSI had the first 1.125 shaft, it's unbreakable.

Ringing off the shaft/spline at the converter is a mistimed shift.

The weak link on the 1.125 is the stator tube, so run a spragless converter on that.

sounds like the coan has had good success compared to other, 1.125 would be a nice upgrade in the future.

I put 1400-1500 on a ringed, standard sized NASA input shaft from trans specialties, put them in alot of customer transmissions that are at that power or less. No need in a 1" + shaft unless you are planning on making 1500+

ATI ringless, rings are in the pump stator, no issues.