There are various bump and rebound stops used on IRS cars

The following guide might be useful: -

140290: large bump stop fitted to TR4A body

136758: 1.626" tall. Rebound and bump stop TR4A, 250, 5, TR6CP, CC. Fitted up to Comm. No. CC61570 and CP52867. Bump rubber only from Comm. No. CC61571 and CP52868 and all CF, CR

155719 1.25" tall. Rebound Fitted from Comm. No. CC61571 and CP52868 and all CF, CR