I found mine at Byerly RV Eureka MO 63025 $5.99 shipping $3.00. Their email is below
This is the Acorn lens, our # 236418 & 236419 both $5.99 plus shipping. Would you like clear or amber? I will then email an invoice, will call for a credit card number and we can ship it out for you.
Steve S.
ByerlyRV.com
1-800-878-3325
parts@byerlyrv.com