Once in HeinOnline, select American Law Institute Library > Restatements & Principles of the Law > Trusts
Select the series you are interested in. Drafts are located below the Official Text in reverse chronological order.
Westlaw, available on the library's Westlaw computers, also includes select drafts for the Restatements of the Law.
Once in Westlaw, from the the All Content tab, select Secondary Sources > Restatements & Principles of the Law > Trusts > Restatement of the Law - Trusts Archive (located in the Tools & Resources box on the right)
Jenkins has select drafts in print and on micro in the library. Search the Jenkins' catalog for Restatement* Draft* Trust* for a full list of available drafts.