I'm interested in general pre-ERISA vesting restrictions. Particularly those in effect in 1968. For example, was 15 year cliff a permitted vesting schedule?

Try to get a copy of CCH Pension Plan Guide 159, dated April 14, 1978. Title "Vesting Under ERISA" by Isidore Goodman. [aside for those who, like me, are long in tooth - one moment of silent reverence as we face East ]

Generally, prior to ERISA, vesting (in qualified plans) was required only upon attainment of nra in a pension plan or some triggering event in a profit sharing plan, and upon termination of a plan or the complete discontinuance of contributions.

Keogh plans (HR10) had a 100% requirement for employees.

Companies had a wide range of vesting schedules which were completely voluntary on their part.

Sometimes plans voided vested benefits under "bad boy" provisions.

Before ERISA and its related changes, retirement plans were meant to reward employees who stayed with a company until retirement. There was no real attempt to provide a severance benefit in a retirement plan - which, unfortunately, is where most defined contribution plans find themselves now - severance plans and not retirement plans.

[once in a while, a political thought envelops my comments .. my hope is these are not considered "high crimes and misdemenaors.."]

The pre-ERISA vesting rules were included in "old" section 411(e) of the Code. They required only that benefits become fully vested (to the extent funded) only upon partial or complete plan termination. Also, the pre-ERISA non-discrimination rules prevented a vesting schedule that discriminated in favor of officers, shareholders, supervisors or the highly-compensated. Long cliff vesting of the kind you describe was permitted. In fact, it was the loss of pension benefits by fairly long-term employees under this rule that was in part responsible for the passage of ERISA.

The pre-ERISA rules live on--sort of--in the governmental plan area, since vesting under these plans is still subject only to the pre-ERISA qualified plan rules.