I did a quick search for your specific pattern and the only one that came up was sold. I think you could find something similar from Kwik Sew...they have quite a few easy fit pullover dresses. They don't sell patterns from their site but they have a store locater and some online dealers listed.
Otherwise, eBay is worth searching. I've found many patterns there that are out of print for a good price.

Here is a link that might be useful: Kwik Sew Patterns

I have a favorite dress pattern similar to your #6066 - I've made this dress 10 (yes! TEN) times. It is loose fitting and comfortable in summer made in linen or cotton.

{{!gwi}}

I just checked my patterns - I don't have that particular pattern, but do have McCalls 8720, which is also a t-shirt style dress. Size 12-14-16, I believe ...

Holler if this suits your needs...

DonnaR/CA

Thanks so much, everyone. I managed to get my hands on it in a size too large (18-20-22), not as bad as it sounds if you read the measurements, just have to try to whittle it down a little. Noinwi, I checked KwikSew first. Teresa, I have 2 of those dresses and love them. Donna, thanks for looking. If you want to know what set this scavenger hunt off, go to www.theterritoryahead.com and look at the layered t-shirt dress for $79!!! Are they kidding?