I am working with a legacy product that uses a Dual Mono-stable Multi-vibrator. The part designed into the product is an MC74HC4538AD. The component uses an old design architecture that defines pins 1 and 15 as ground pins. The capacitor in the RC timing network has one side connected to pin 2 (C/R) and the other side terminated to ground. Sources here would like to use a TI CD74HC4538M as a drop-in replacement. However the pin-out is a little different. Pins 1 and 15 are to be used to terminate the negative side of the timing capacitor instead of grounding the capacitor externally.
My questions are
Will there be any ill effects to the CD74HC4538M using it in the old style configuration with pins 1 and 15 grounded?
Why was this minor architectural change made to the device?