We are not a HMDA reporter so when appropriate, we collect demographic info based on Reg. B requirements. Is there a version of the new 1003 that only has the Reg. B aggregate collection section? All I can find has the disaggregate version that HMDA reporters would use.

I do not see it as an issue as the information is interchangeable, whether or not you are a HMDA reporter.
Official Interpretation
13(a) Information to be requested.

7. Data collection under Regulation C. For applications subject to § 1002.13(a)(1), a creditor that collects information about the ethnicity, race, and sex of an applicant in compliance with the requirements of appendix B to 12 CFR part 1003 is acting in compliance with § 1002.13 concerning the collection of an applicant's ethnicity, race, and sex information. See also comment 5(a)(2)-2.

8. Application-by-application basis. For applications subject to § 1002.13(a)(1), a creditor may choose on an application-by-application basis whether to collect aggregate information pursuant to § 1002.13(a)(1)(i)(A) or disaggregated information pursuant to § 1002.13(a)(1)(i)(B) about the ethnicity and race of the applicant.

I agree with Randy that it won't be an issue under Regulation B. Plus, there is no regulatory requirement to use the URLA/1003, but check with your investors (if you sell your loans) to see if they have a requirement.