Plan merger - different plan years/ different vesting methods

[Guest qualified plan]

Plan A (described below) is merging into Plan B (see below) on 6/30/02. How must Plan B count years of vesting service for Plan A participants (cites please)?

Thanks in advance!

_________________________________________________

2 401(k) Plans:

Plan A: 1 year of vesting service for each Plan Year in which participant completes 1,000 hours. Plan Year = 7/1/-6/30

Plan B: 1 year of vesting = elapsed time of 12 months starting from the participant's date of hire. Plan Year = calendar year.

[Guest pjb]

See 411(a)(10)(B) but also see 1.410(a)-7.