Schematic question - SA 20 PA amp

[fried_amps]

There's a difference between the schematic shown in the 'SA 20 - page 1' link and the schematic in the all-in-one file (on the Schematics page of the site).

On the 'page 1' version, these mods are shown:
Change to the value of R2 near TP-4, from 680 to 1K
Addition of 27K resistor between R2 and C4
Addition of 47uf cap between C23 and R31

Any idea if these mods are valid?

[Don T.]

Hello:
 I believe those mods were incorporated by Fender right after the buy out. It was just to give the input more stability and an industry standard input impedance. Frankly non of my amps had the mods and have been working for 20 years.
Don T.