The Thompson Research Group LLC (TRG) suggested to its investor clients on Monday (June 22) that it hold onto its shares of Thor Industries Inc., Winnebago Industries Inc. and Drew Industries Inc.

TRG’s latest “Industry Update” was prompted by the release earlier in the day of the April towable retail sales figures from Statistical Surveys Inc. The Grand Rapids, Mich.-based firm reported that April sales totaled 13,981, off 39.5% from April 2008.

TRG noted in part, “Towable retail sales were flattish in April (down 39.5% vs. 39.0% in March). Based on our recent RV dealer survey (published 6/3/09), we believe that sales have improved modestly since that time. Retail sales continue to outpace wholesale shipments, as dealers still remain acutely focused on managing inventory levels down further. That said, the gap between retail and wholesale is not nearly as pronounced as the gap for motorhomes. As we have discussed in previous reports, we believe Thor, Winnebago and Drew Industries eventually will be the survivors from this steep downturn. Thor’s financial strength has enabled it to prosper relatively better than other competitors in the current environment.”

For its rating, TRG says it gives a “hold” rating when the estimated total return potential of a given stock is greater than or equal to 0% and less than 10%.