diff between a 518 and 618 trans?

Is the difference lockup and non lock up for 618 and 518?

That's not it, there's lock up and non lock up 518's. I know of no non lock up 618's. I think 618's were only behind V-10's and Diesels. Where is Gary when you need him?

Number of clutches... these models are also known as the 46Rx and the 47Rx (x being either 'H' for hydraulic governor or 'E' for electronic governor)

thanx, what i am trying to do is identify the trans in my 95 2500 with the cummins, it is a lockup converter but it says standard duty on the equipment plate. it's gettin ready to go after 274k miles and I need to find another for it. Converter kicks out of lockup and i have replaced the filter twice in the last month, showing aluminum in the pan. No steel tho, magnet is spotless.

It's a 47RH - the only transmission fitted to the V10 and diesel engines in that year.

Are you sure the 'standard duty' isn't referring to the transfer case? That had a std. duty/heavy duty option - not the transmission.

its 2wd

this thing is weird tho, it says 10/94 on the date of build , but has the 96 color code on the firewall tag and is obdII