R Model Engine Numbers/codes

[25002500]

Got a newbie question

On an R686, R688, R690 what do the last two numbers stand for or represent.

I have been told the engine number, but what specifically is the difference between all of these?

[Superdog]

Got a newbie question

On an R686, R688, R690 what do the last two numbers stand for or represent.

I have been told the engine number, but what specifically is the difference between all of these?

R686 - the original designation for 86 was the ENDT-676 300 series Maxidyne.In later production,it also cover the 300 hp E6.

R688 - the original designation for 88 was the ENDT-678 350 hp,later become the E6-350.Later on 88 covered all E6 & later E7 "Econdyne" engines

R690 - 90 covered all E6 & E7 Maxidyne engines in later production

I may be wrong but I don't think any straight R models ever came out with the E7's,just the later RD & RB models.